Retrofitting and Rehabilitation of High Rise Fire Damaged Concrete Building Master Thesis Study Course Construction and Real Estate Management Submitted on 15.09.2014 Haseeb Uz Zaman 541108 First Supervisor: Mika Lindholm Second Supervisor: Dieter Bunte Abstract Study has been aimed to establish a structured solution for rehabilitation and retrofitting of fire damaged concrete buildings. This study explains the rehab process of fire damaged concrete buildings in three basic categories; condition evaluation, decision making, rehabilitation & retrofitting. Evaluation method of damaged building has been based upon understanding of material properties at elevated temperatures, condition survey and condition assessment. Condition survey includes visual inspection, hammering and chiselling techniques whereas condition assessment includes both non-destructive and destructive tests that are selected upon the basis of efficiency, economy, and performance. Feasibility study is required to make right decisions for the rehab of fire damaged building. Such a feasibility study should include all important aspects that will have an impact in the future, therefore must be considered in decision making. A new feasibility analysis model is developed as a part of research. It is expected to help decision making process because of its sound conceptual foundation and detailed structure. If feasibility study reveals rehabilitation and retrofitting worthwhile then it can be effectively rehabilitated with the help of right techniques. Rehabilitation of non-structural members/elements and retrofitting of structural with the help of soda blasting, patch repair, FRP reinforcing, partial removal and replacement, concrete jacketing, steel jacketing and few other retrofitting techniques has been discussed. Respective pros and cons of these techniques have been covered with special focus on sustainability, economy, efficiency and limitations. These techniques can be used separately or in conjunction with other techniques. As every locks has its own key similarly every case has its unique solution therefore it can’t be said that which technique or set of technique is universally superior to others. Generally speaking, partial removal and replacement offers more advantages. It seems to have more ticks and less crosses when compared to others. Keywords: Fire, Damage, Evaluation, Decision, Analysis, Retrofitting, Rehabilitation Table of Contents Table of Figures ……………………………………………………………….….… I List of Tabulation …………………………………………………………………... II List of Abbreviations ……………………………………………………….….….. III 1 Introduction ................................................................................................ 1 1.1 Background ............................................................................................... 1 1.2 Goals and bounds of the study ................................................................. 1 1.3 Research questions .................................................................................. 2 1.4 Research methodology ............................................................................. 3 2 Assessment of fire damaged building ...................................................... 4 2.1 Behaviour of materials during fire.............................................................. 4 2.1.1 Concrete ............................................................................................... 4 2.1.2 Steel...................................................................................................... 7 2.1.3 Other Materials ..................................................................................... 8 2.2 General assessment of building ................................................................ 9 2.2.1 Type of structure ................................................................................... 9 2.2.2 Scope of damage .................................................................................. 9 2.2.3 Size, duration and temperature of fire ................................................. 10 2.3 Condition assessment of non-structural members and utilities ............... 10 2.3.1 Visual Inspection ................................................................................. 11 2.4 Condition assessment of structural members ......................................... 12 2.4.1 Visual Inspection ................................................................................. 12 2.4.2 Field Testing ....................................................................................... 16 2.4.2.1 Schmidt/Rebound Hammer ........................................................... 17 2.4.2.2 Ultrasonic Pulse Velocity .............................................................. 18 2.4.2.3 Windsor-Probe or Penetration Resistance test ............................. 20 2.4.2.4 Core Sampling and Testing........................................................... 22 2.4.2.5 Deflection measurement with digital theodolite ............................. 24 2.4.3 Laboratory testing ............................................................................... 24 2.4.3.1 Petrography .................................................................................. 25 2.4.3.2 Tensile Test .................................................................................. 27 2.4.3.3 Scanning Electron Microscopy (SEM) ........................................... 28 3 Rehabilitation and Retrofitting of fire damaged building...................... 31 3.1 Cleaning .................................................................................................. 31 3.2 Removal of smoke odour ........................................................................ 33 3.3 Rehabilitation of non-structural members and utilities ............................. 35 3.4 Retrofitting of structural members ........................................................... 37 3.4.1 Fibre Reinforced polymer (FRP) ......................................................... 38 3.4.2 Partial removal and replacement of concrete and reinforcement ........ 44 3.4.2.1 Removal of concrete ..................................................................... 45 3.4.2.2 Partial replacement of reinforcement bar/bars .............................. 47 3.4.2.3 Partial replacement of Concrete.................................................... 48 3.4.2.4 Advantages & disadvantages of partial removal & replacement ... 49 3.4.3 Concrete jacketing .............................................................................. 51 3.4.4 Steel Jacketing.................................................................................... 54 3.5 Other Methods of retrofitting and rehabilitation ....................................... 56 4 Feasibility study ....................................................................................... 60 4.1 Technical Aspect ..................................................................................... 61 4.1.1 Technical aspects of structural members ............................................ 61 4.1.1.1 Columns ........................................................................................ 62 4.1.1.2 Beams ........................................................................................... 64 4.1.1.3 Floor/Slab Panels.......................................................................... 65 4.1.2 Technical aspects of non-structural members..................................... 67 4.2 Financial Aspect ...................................................................................... 67 4.2.1 Preliminary requirements .................................................................... 68 4.2.2 Structure ............................................................................................. 68 4.2.3 Realization of all associated costs ...................................................... 69 4.2.4 Realization of incomes ........................................................................ 69 4.2.5 Analysis calculations by analysis tools ................................................ 70 4.2.5.1 Payback period ............................................................................. 70 4.2.5.2 Financial ratios .............................................................................. 71 4.2.5.3 Net Present value ......................................................................... 71 4.2.5.4 Internal rate of return .................................................................... 72 4.2.6 Risk analysis ....................................................................................... 73 4.2.6.1 Sensitivity analysis ........................................................................ 74 4.2.6.2 Scenario analysis ......................................................................... 74 5 Results, findings and problem Definition............................................... 76 5.1 Results .................................................................................................... 76 5.2 Findings and problem definition .............................................................. 78 6 Solution development .............................................................................. 80 6.1 Technical feasibility analysis tool ............................................................ 80 6.1.1 Degree of Complexity “C” ................................................................... 80 6.1.2 Life expectancy of solution “L” ............................................................ 81 6.1.3 Time required for proposed solution “T” .............................................. 82 6.1.4 Degree of damage “D” ........................................................................ 82 6.1.5 Parametric mathematical model.......................................................... 83 6.1.6 Example Calculation ........................................................................... 84 6.2 Financial feasibility analysis tool ............................................................. 88 6.2.1Depreciation ......................................................................................... 90 6.2.2 Maintenance and Operation ................................................................ 91 6.2.3 Interest ................................................................................................ 91 6.2.4 Tax ...................................................................................................... 92 6.2.5 Insurance ............................................................................................ 92 6.2.6 Special Costs ...................................................................................... 93 6.2.7 Annual Costs....................................................................................... 93 6.2.8. Annual income ................................................................................... 94 6.2.9 Working methodology and example .................................................... 94 6.3 Feasibility analysis tool ........................................................................... 97 7 Trial of feasibility analysis tool ............................................................... 99 8 Conclusion, scope, recommendation, critique & summary of study 108 8.1 Conclusion ............................................................................................ 108 8.2 Recommendations ................................................................................ 110 8.3 Scope .................................................................................................... 111 8.4 Critique .................................................................................................. 111 8.5 Thesis Summary ................................................................................... 111 9 List of Literature……………………………………………………………..118 I Table of Figures Figure 1: Pink texture of fire damaged concrete ............................................... 13 Figure 2: Schmidt hammer test on fire damaged concrete structure ................. 17 Figure 3: Penetration Resistance ...................................................................... 21 Figure 4: Core obtained by drilling .................................................................... 23 Figure 5: Colour of aggregate in Petrography test .......................................... 27 Figure 6: Universal testing Machine for tensile test........................................... 27 Figure 7: Soot cleaning from Ceiling ................................................................. 33 Figure 8: Thermal fogger (A), Ozone Machine (B), .......................................... 35 Figure 9: Air Scrubber ....................................................................................... 35 Figure 10: Soda-blasting ................................................................................... 37 Figure 11: FRP plate application beneath the beam ......................................... 40 Figure 12: FRP Wraps on side faces and bottom side ...................................... 40 Figure 13: FRP sheets wrapped around the Column ........................................ 41 Figure 14: FRP sheet wrapped on the tension side of fire damaged slab ......... 41 Figure 15: Hydro Blasting for concrete removal ................................................ 46 Figure 16: Shotcrete to replace removed damaged concrete ........................... 49 Figure 17: Concrete jacketing process before concreting ................................. 51 Figure 18: Steel jacketing process .................................................................... 54 Figure 19: Steel jacketing of column ................................................................. 55 Figure 20: Fire Damaged Concrete Column ..................................................... 62 Figure 21: Fire Damaged Slab .......................................................................... 65 Figure 22: KBP Coil Coaters ............................................................................. 84 Figure 23: Top view of damaged Valley- Ridge concrete roof ......................... 86 Figure 24: Beverly Centre Islamabad ................................................................ 99 Figure 25: Fire damaged Beverly Centre Islamabad....................................... 100 Figure 26: Burnt AC unit (left), Damages Electricity cables (right) .................. 100 II List of Tabulation Table 1: Mineralogical and strength changes in concrete at different temperatures …………………………………………………………………………...6 Table 2: Non-structural members’ and utilities’ visual inspection report ............ 11 Table 3: Hammer sound test criteria for concrete’s strength ............................. 14 Table 4: Hammer and Chisel test criteria for concrete’s strength...................... 15 Table 5: Visual Inspection Guide for fire damaged R.C.C elements ................. 16 Table 6: Technical feasibility study of column retrofitting .................................. 63 Table 7: Technical feasibility study of Beam Retrofitting ................................... 65 Table 8: Technical feasibility study of Slab Retrofitting ..................................... 66 III List of Abbreviations AEW Annual Equivalent Worth BS British Standard C Celsius DTA Differential Thermal Analysis FFS Financial Feasibility Score FRP Fibre Reinforced Polymer GFRP Glass Fibre Reinforced Polymer HVAC Heating Ventilation Air Conditioning HS High Strength IRR Internal Rate of Return ISO International Organisation of Standardization LCC Life Cycle Costing MARR Maximum Attractive Rate of Return NDT Non Destructive Testing NPV Net Present Value PP Profit Percentage RCC Reinforced Cement Concrete SEM Scanning Electron Microscopy TGA Thermo Gravimetric Analysis TR Technical Report UPV Ultra Pulse Velocity UTM Universal Testing Machine 1 1. Introduction 1.1. Background Many books, journals and articles have been written over different aspects of fire damage buildings e.g. evaluation of fire damaged buildings, NDTs for fire damaged buildings, rehabilitation of fire damaged buildings, retrofitting of structures subjected to high temperatures etc. Many Studies and researches have been done on various aspects too. But still a crying need have been felt for a structured study that takes care of matter right from the beginning (evaluation) and encompass the whole process till the very end (rehabilitation and retrofitting measures). 1.2. Goals and bounds of the study This study is inspired to take care of whole process. The process starts from evaluation of fire damaged buildings. Various techniques for evaluation of concrete structures are available and commonly practiced but not every technique is suitable for evaluation of fire damaged building. It has been set as a goal to explore different methodologies and discuss most suitable and most practiced ones in the text. Then to explain their limitations and shortcomings to work out that which technique or combination of techniques can provide with the true assessment of the fire damaged concrete building. After evaluation, process proceeds to technical and financial analysis, which leads to decision making. It is targeted to structure feasibility study that would consist both financial and technical aspects. After decision to rehab the building is made and considered as worthwhile then study will dictates different rehabilitation and retrofitting measures that can be used to bring building back to its normal functionality. It is targeted to analyse the measures on basis of sustainability and future fire proofing as well along with their respective pros and cons. So that suitable method can be used according to the situation and case 2 on hand. This study is limited for concrete buildings with focus on research questions only. 1.3. Research questions Research question presented in the conceptual formulation were in preliminary stage and having few corners to be smoothed. Last question in the conceptual formulation “How to manage site work (building damaged by fire)?” has been omitted with agreement, as it is not consistent with the study goals and bounds. Further, language and structure of few research question has been improved. Question no 4 and 5 in conceptual formulation have been merged together and little improvement is made by elaborating it in bit more detail. Similarly question 7 and 8 in conceptual formulation were not very clear, so they have also been elaborated. Finally research questions are as follow i. How to conduct condition survey and condition assessment? ii. What tests and field inspections are required? iii. What can be done with buildings that are damaged because of fire (Demolitions, Re-use etc.)? iv. Is it possible and feasible to retrofit the structural components and rehabilitate the building concerning the damage they have endured (Technical feasibility)? v. Is it financially feasible to retrofit and rehab the fire-damaged building? vi. How to rehab the building (non-structural components)? What possible treatments are feasible in light of economy, sustainability, building functionality etc.? vii. How to retrofit structural components? What possible treatments are feasible in light of economy, sustainability, fire protection, building functionality etc.? viii. What is the Scope of research findings/conclusions? 3 1.4. Research methodology At first literature study has been done in which evaluation of fire damaged buildings and rehabilitation & retrofitting were covered. The knowledge obtained from literature study is then skimmed to include only targeted methodologies that ticks certain criteria (as explained in section 1.2). Afterwards, development and research work has started. In this phase, parametric mathematical model for feasibility analysis had been developed based on technical and financial feasibility. After it has been developed initially, then it has been tested. Shortcomings have been identified and developed model is improved. This becomes a loop of testing and improvement until satisfactory results are obtained. After parametric mathematical model had been finally developed, it had been tested on a real case (Beverly Centre Islamabad) to test its capacity and validity. So conclusively, following research methods have been used   Literature  Interviews  Case studies  Internet sources  Data collection  Parametric mathematical modelling Empirical testing 4 2. Assessment of fire damaged building After the incident of fire, the buildings are in bad condition. The severity of the damage depends upon the duration, magnitude and temperature attained by fire. After fire is extinguished, building has to be immediately investigated to decide that; is it safe to enter the building and can building withstand after the fire load, without being progressively collapsed. After structure of the building is secured, it is ready to be properly assessed. The condition assessment requirements, techniques (field tests, laboratory testing etc.), methodology for data management of collected data1 will be discussed in this chapter. 2.1. Behaviour of materials during fire Buildings are consisting of construction materials that vary in nature from one another. The very nature of each material is specific to its physical properties, chemical properties and behaviour of material, when exposed to fire. The most important materials found in the concrete buildings is obviously concrete and structural steel but even in them, we have variations depending upon the manufacturing process and ingredient mix. Other materials like glass, aluminium, thermal insulations, wood, plastics etc. are also part of building. Investigate of the damage occurred to the building, requires the understanding of these materials especially those which are part of the structural elements. Now, we will discuss the behaviour of basic structural materials (concrete and steel). 2.1.1. Concrete Concrete is a very stable material in nature. It is inert, solid, with high compressive strength and excellent surface hardness. The melting point of concrete is around 1 To be utilised for technical and financial feasibility. 5 1200 Celsius Centigrade (Concrete Society TR68, 2008). All these properties makes it quite subtle when exposed to fire. EN 13501-12 classifies materials into seven categories (A1, A2, B, C, D, E and F). A1 is considered as the best possible material which is virtually inert to fire or fire resistant and concrete is assigned under A1 category. Concrete doesn’t burn by itself because it is not a combustible material hence doesn’t add up in the fire load. It doesn’t melts and doesn’t drips materials at the temperature that normally occurs in fire. The inert property of concrete is down to the ingredients in the concrete mix which gives it these inert properties. Moreover concrete has poor thermal conductance and it transfers heat at a very low rate.3 The rate of temperature increase through cross section is also slow. The temperature of the material at the surface wouldn’t be that high after initial few centimetres. According to a standard ISO 834/BS 476 fire test performed on a concrete beam of cross section 160mm x 300mm showed that after exposure of concrete from 3 sides for 1 hour, the surface temperature reached to 900 Celsius. This decreases to only 600 Celsius after 16 mm and to 300 Celsius after 42mm. So actually the temperature gradient decrease from 900 to 600 in depth of 16 mm and from 600 to 300 in depth of 26mm.4 This behaviour of concrete makes it structurally sound enough even in intense fires and structure avoids collapse. The strength remaining in the concrete after it is cooled down depends upon number of factors like  Temperature attained by concrete (not the temperature of air or the  temperature of flames)  Aggregates present in concrete  Duration of fire  Concrete batch mix proportion and Load beard by structure during fire 2 European standard for building materials classification for the reaction to fire behaviour of building products. 3 4 The Concrete centre. 2008. Concrete and fire safety. Page no 4. The Concrete centre. 2008. Concrete and fire safety. Page no 4. 6 All these factors effects the strength of concrete after the event of fire. Upto the temperature of 300 Celsius, concrete more or less retains is strength and this is also considered as the benchmark of safe temperature of concrete. Upto the temperature of 500 Celsius a significant loss of strength happens but still holds sufficient residual strength. Above 600 Celsius serious damages occurs. Concrete Society document TR68, 2008 explains the behaviours of concrete at different temperatures and shown in Table 1.5 Heating Mineralogical changes Strength changes Temperature (Celsius) 70-80 105 Dissociation of ettringite Loss of physically bound that water in aggregate and cement matrix commences, increasing capillary porosity 120-163 Decomposition of gypsum 250-350 Oxidation of iron compounds causing pink/red discolouration of aggregate. Loss of bound water in cement matrix and associated degradation becomes more prominent 450-500 Dehydroxylation of portlandite. Aggregate calcines and will eventually change colour to white/grey 573 5% increase in volume of quartz (α­to β­quartz transition) causing radial cracking around the quartz grains in the aggregate 600-800 Release of carbon dioxide from carbonates may cause a considerable contraction of the concrete (with severe micro-cracking of the cement matrix) 800-1200 Dissociation and extreme thermal stress cause complete disintegration of calcareous constituents, resulting in whitish grey concrete colour and severe micro-cracking 1200 1300-1400 Minor loss of strength possible (<10%) Significant loss of strength commences at 300ºC Concrete not structurally useful after heating in temperatures in excess of 500– 600ºC Concrete starts to melt Concrete Melted Table 1: Mineralogical and strength changes in concrete at different temperatures6 5 Jeremy P Ingham. 2009. Forensic engineering of fire damaged concrete structures. Page no 2. Concrete Society. 2008. Technical Report No. 68 – “Assessment, Design and Repair of Firedamaged Concrete Structures”. 6 7 In event of fire, the structure should perform these following three limit state functions.7    The structure should retain its load bearing capacity The structure should protect inhabitants from harmful smoke and gases The structure should protect people from the heat of fire Fire causes changes in pore pressure, temperature and moisture levels in concrete and due to these changes concrete loses its strength but whatever the scenario is, the structure must perform at these three fire limit states successfully. To achieve that, concrete shouldn’t have following changes   Loss of compressive, shear and bending strength Loss of bonding between steel and concrete To avoid these two changes, following two factors have to be considered more important than others in case of concrete.  Overall dimension of concrete; so that the temperature shouldn’t be allowed to elevate throughout the cross-section of concrete element (as experienced in standard fire test that temperature gradient in concrete is quite steep. Temperature drops from 600 Celsius to 300 Celsius in only 26  mm) Concrete cover; as steel is having stresses locked in it. These stresses will be released if the steel will expand as it normally does on high temperature. For structural conventional reinforcement this limiting temperature is 500 Celsius centigrade and for pre stressed concrete this limiting temperature is 350 Celsius centigrade. Therefore cover should be thick enough that it will comprehensively reduce the temperature at the depth where reinforcement bars are available.8 2.1.2. Steel Steel experience damage and loss of strength when exposed to high temperature. Steel has high thermal conductance which can be held responsible 7 8 Fire limit states described in British and Euro Code 2. The Concrete centre. 2008. Concrete and fire safety. Page no 6-7. 8 for the spread of fire. The loss of strength in case of high temperature is generally responsible for the extra deflections of R.C.C elements. Mostly after cooling down, steel recovers its yield strength if it has experienced temperature less than 450 Celsius in case of cold rolled steel and 600 Celsius in case of hot rolled steel. If the temperature is under these respective limits then steel can be re-used comprehensively and structure can be retrofitted with various measures available. But if temperature is exceeded in these respective kinds of reinforcing steels then it will be a problem, as in that case replacement of reinforcement bars or additional bars will be required (will be discussed in detail later). 9 Case for pre-stressed steel is more critical one than reinforcing steel as the nature of the pre-stressed structure. Elongation of steel is done by hydraulic jack and then concrete is casted over it. When steel has enough bonding with concrete then steel wires are cut and released. They tends to squeeze inside but the bonding with the concrete prohibits it, as a result of which the pre-stressing steel inserts inwards/compression force on concrete. This compression force counter acts the tensile load acting over it. If temperature will rise then pre-stressing steel will lose the tensile force within itself which is causing the compression in concrete and ultimately structure will lose its strength. From 200 to 400 Celsius, reinforcements in pre stressing concrete structure lose considerable strength. At 400 Celsius, structure loses its 50% strength. In terms of re-use more important factor is the tension available in pre stressed steel after the event of fire. If it still has significant loss of tension then it may not carry its intended function.10 2.1.3. Other Materials Other non-structural materials like glass, aluminium, wood and all such other materials experience damages in event of fire and may contribute to the fire load by themselves. These materials are not of much significant importance as they can easily be replaced if damaged beyond repair. Materials may exhale harmful fumes or gases or particles in air especially asbestos. If building has asbestos in 9 Jeremy P Ingham. 2009. Forensic engineering of fire damaged concrete structures. Page no 3. Jeremy P Ingham. 2009. Forensic engineering of fire damaged concrete structures.Page no 3. 10 9 it and it caught fire then asbestos particles will be released in air although their concentration will not be very high at least upto the level where it will be critically dangerous but constant exposure to these particles will lead to serious health risks. One of the prime responsibilities of the building disaster department is to confirm or discard the presence of asbestos in the building. Once building is regarded as asbestos free then experts and crew can enter the building for examining it. 2.2. General assessment of building After the event of fire, building is in poor condition. When authorities are done with preliminary survey to decide that building is safe enough to enter then assessment team can start the assessment of building but before that a general analysis of building is required to know following facts and figures about the case. 2.2.1. Type of structure Building type is an important measure to realise. Which elements are most important ones for the stability of the overall structure and what load pattern is existing in the building are important questions. It is of asset to understand the building materials and usage of building as well. It is handy to understand the type and structure itself from the plans and shop drawings of the building and marks the most critical ones. This will make the further assessment process more time saving and easy as well. 2.2.2. Scope of damage It is better to visit the site and conduct complete condition assessment but preliminary report from fire and police department can be studied to have a general idea about the damages building has incurred. This will make an initial image and inform about the building’s damage at a crude level. Answer to basic 10 questions like how much area or stories have been damaged and how much got indirectly effected can be obtained from the Fire department/Police report. 2.2.3. Size, duration and temperature of fire Duration, size and if possible then temperature of fire can also be determined from the fire report and it will be a real assert for the upcoming stages of assessment. Duration of fire is a very important factor in particular. Fire resistance of the building is expressed in unit of time as it defines11 Fire resistance is a period of time for which an element of construction (beam, column, floor, wall, etc.) will survive in a standard fire test carried out in an approved furnace under specified condition of temperature, imposed load and restraint Hence duration of fire will give an idea what kind of damage building would have undergone in the event. Interviews recorded from the inhabitants and witnesses can give an idea about the fire path which also have impact on the damage undergone and obviously on the duration of fire exposure. Desk study before visiting the site and conducting general assessment is very beneficial. It is always better to do homework before dealing with the case. It will create an initial picture and equip the inspector with the valuable information regarding structure, its properties and its materials. 2.3. Condition assessment of non-structural members and utilities Non-structural members of the building like doors, windows, ventilators, partition walls, façade, thermal insulations, floor coverings etc. bear heavy damages often in case of fire. They just not get damaged but many times adds to the fire load of 11 IstructE – Introduction to the fire safety engineering of structures. 11 the building during the event. Ideally they are assessed during visual inspection. There is no need to conduct excessive testing on these parts or utilities of the building. Visual inspection of the building with a team of crafts men can determine the condition of the utilities or non-structural members. 2.3.1. Visual Inspection Eye of an experienced engineer is more valuable than any other tool in the condition assessment of non-structural members or utilities. A team consisting of experts/craftsmen in respective field can conduct this task. Table 2 will give a comprehensive insight about the important things to be inspected during visual inspection Item Nature of damage (FD, WD, SD, ID, BW)12 Damage rating Description Recommen dation (1--5)13 Windows Doors Detached Balconies Roof Covering (Shingles, Tiles etc.) Partition Walls Façade Elements HVAC Plumbing Electrical wirings Railings Flooring material Dropped ceiling Light Fixtures Alarm System Mechanical equipment Table 2: Non-structural members’ and utilities’ visual inspection report 12 FD= fire damage, SD= Smoke damage, WD= Water damage, ID= Internal damage, BW= Bio waste like blood, carcases etc. 13 1= needs cleaning, 2= needs surface treatment (polishing shinning etc.), 3= needs minor repair, 4= needs major repair, 5= Replacement. 12 While assessing the condition of utilities and non-structural part of the building nature of damage has to be determined to realise that what was the cause of damage. Either it was because of fire or because of water or fire extinguishing foam that fire brigade have used or damage has been done due to smoke etc. Once cause of damage is recognised then extent of damage is assessed and probably be given rating from 5 to 1. Five is the worst case scenario where only replacement is the option. While giving utilities the damage rating then eye should be kept upon the price factor. 2.4. Condition assessment of structural members Condition assessment of structural members is very vital part of condition assessment. Structures’ damage is bit technical to estimate and recognise. Structural condition assessment is done by the help of various methods which includes various laboratory testing, field inspection and field testing. During the general assessment or desk study of the building the type of building and its structure is studied. Afterwards a complete strategy is developed about the structural assessment. It would be easier to approach each kind of structure individually (e.g. columns, beams, roof, slab etc.), especially in visual inspection. 2.4.1. Visual Inspection Visual inspection is a very powerful tool and one of the most common and oldest available non-destructive testing techniques available. Visual inspection gives a wealth of information about the structure and its condition but has certain requirements and limitations. Visual inspection can only be governed by a technically sound professional who has knowledge about structure, material science and construction methodologies. Visual inspection only gives impression of visible issues and hidden issues remain unnoticed. It also doesn’t give us any quantitative information about the properties of the material. Due to these 13 limitations, often visual inspection is not sufficient and has to be supplemented by other non-destructive and partially destructive testing techniques.14 Visual assessment of a fire damaged concrete structure is practiced to observe the heat patterns, change in colour of concrete, spalling of concrete, cracking in concrete, any visible deflection of structural members like load bearing walls, beams, roof etc. Cracks in concrete due to deflection may be present in the structure before the event of fire but still it is advisable to consider them during inspection. Normally concrete is considered as fire resistant and non-combustible material but if the temperature of concrete reaches upto 300 Celsius then oxidation of iron compounds in the aggregates and cement paste occurs and it gives a pink texture to the concrete. Pink colour of concrete refers to the damaged concrete and indicates towards the fact that concrete can’t be used anymore. At higher temperatures that usually doesn’t occur in building fires, concrete turns it’s colour to whitish grey and then to yellowish-brown colour ultimately. So care has to be taken while observing the damage of concrete with reference to its colour.15 Figure 1: Pink texture of fire damaged concrete16 Tapping with a hammer and chisel is also one of the oldest methods to inspect the strength of concrete. This is not an exact methodology to estimate concrete 14 http://www.engineeringcivil.com/visual-inspection-of-concrete-structure.html 10.07.2014. 15 http://www.structuremag.org/?p=4102 accessed 10.07.2014. 16 http://www.structuremag.org/?p=4102 accessed 10.07.2014. accessed 14 strength yet in preliminary assessment, it proves to be a handy method to get some idea of the damage immediately. This technique is highly subjective and depends upon the personal competence. A test hammer of approximately 400 g is hammered against the concrete at elbow height. The sound of the impact is used to judge the condition of the concrete. A sharp metallic sound is the indication of strong concrete while a dull thud is an indication of weak and damaged concrete. At spalled surfaces hammer test can’t be used. The table 3 below give us the criteria for concrete’s strength17 Strength of concrete (N/mm2) Results of Blow of hammer (0.4 kg) upon concrete surface Below 6.0 Sound-toneless deep Dent at impact surface with crumbling edges 6.0 to 10.0 Sound-slightly toneless. Dent at impact surface has smooth edges, concrete crumbles 10.0 to 20.0 Sound-clear At impact surface a whitish mark remains Above 20.0 Sound-ringing metallic At impact surface there is a mark-visible Table 3: Hammer sound test criteria for concrete’s strength 18 Chisel and metallic pencils are also used for the evaluation of concrete’s strength and the depth of damage that has occurred. In this case hammer is placed at the right angle to the surface and then stroked form behind with the hammer. The results of the practice gives the idea about the concrete’s strength and also shows that upto which depth concrete has endured damage. Usually the damaged concrete that already has plane of failure spalled away and exposes the reinforcements. Chisel can also be used to scratch the surface and resultantly can emit some light over the condition of the concrete. Table 4 gives us the criteria for Concrete strength.19 17 http://www.engineeringcivil.com/visual-inspection-of-concrete-structure.html 10.07.2014. 18 http://www.engineeringcivil.com/visual-inspection-of-concrete-structure.html 10.07.2014. 19 http://www.engineeringcivil.com/visual-inspection-of-concrete-structure.html 10.07.2014. accessed accessed accessed 15 Strength of concrete (N/mm2) Below 6.0 6.0 to 10.0 10.0 to 20.0 Above 20.0 Results of Blow of hammer (0.4kg) upon chisel placed at right angles to concrete surface Results of Scratching by chisel Chisel is easily driven into concrete Concrete cuts easily and Chisel can be driven into concrete deeper than 5 mm Visible scratches 1-1.5 mm Thin scales split off round the Visible scratches no deeper mark than 1 mm Mark is not very deep Barely visible scratches crumbles deep Table 4: Hammer and Chisel test criteria for concrete’s strength 20 For visual diagnosis of reinforced cement concrete structural element, following table is assembled. On scale 1 to 5, structural elements can be categorised depending upon various sorts of damages and degree of damage, it has endured. Degree of Observations Damage Colour Finishes Spalling Cracks Deflections Reinforcement 1 (cleaning Usual Unaltered None line None Not observed exposed None Not Observed exposed Minor None Barely structural Observed exposed cracks required) 2 (Surface Hair Usual treatment Surface Slight Cracks but haven’t Peeling required) reached Reinforcement 3 (Minor Repair required) 20 Pinkish/ Reddish Significan t loss Localized Cracks < 25% http://www.engineeringcivil.com/visual-inspection-of-concrete-structure.html accessed 10.07.14. 16 4 (Major Pinkish/ Repair Required) Total loss Extensive Major Minimum Signific- Whitish structural but yet not antly grey cracks significant exposed >25% but <50% 5 Whitish (Replacemen Destroyed Grey t) Total Disintegrated Visible Naked surface concrete significant or deflection >50% lost Table 5: Visual Inspection Guide for fire damaged R.C.C elements21 Visual inspection can give some idea about the structure and its residual strength and has to be supplemented by other NDT and partially destructive tests to create a clear picture of the situation. The results obtained by one team/engineer/craftsman can differentiate from the other as these testing techniques are highly subjective and depends upon personal competence. 2.4.2. Field Testing After visual inspection, field tests have to be performed to get better understanding about the structure and its residual strength. Various kind of field tests are available most of them are non-destructive tests like Schmidt Hammer, ultrasonic pulse velocity etc. Except these non-destructive tests, Core cutter test is also very helpful to understand the structure and gives more accurate results although it is considered as partial destructive test. Location of these field tests have to be carefully decided by an engineer as it has a very obvious effect on the results. 21 Modified from (Concrete Society. 2008. Technical Report No. 68 – Assessment, Design and Repair of Fire-damaged). 17 2.4.2.1. Schmidt/Rebound Hammer A Rebound Hammer is a simple, handy tool used to measure the elastic properties or compressive strength of concrete or rock, mainly surface hardness and penetration resistance. When using it for fire damage structures it has its own limitations and usefulness.22 Figure 2: Schmidt hammer test on fire damaged concrete structure 23 The Schmidt rebound hammer works on the principle that the rebound of an elastic mass depends upon the hardness of the surface against which the mass strikes. When the plunger of the rebound hammer is pressed against the surface of the concrete, it will hit the concrete at a defined energy and the springcontrolled mass rebounds. The extent of such a rebound depends upon the surface hardness of the concrete. The surface hardness, and therefore the rebound, is taken to be related to the compressive strength of the concrete. The rebound value is read from a graduated scale and is designated as the rebound number or rebound index. By reference to the conversion chart, the rebound value can be used to determine the compressive strength. There is little apparent theoretical relationship between the strength of concrete and the rebound number of the hammer. However, within limits, empirical correlations have been established between strength properties and the rebound number.24 22 Haseeb Uz Zaman, Tahir Saleem, Azhar Shehzad, Mohsin Ashfaq & Muhammad Bilal. 2011. Comparison of compressive strength of concrete calculated by destructive and non-destructive testing. Chapter 6. 23 http://www.theconcreteportal.com/nde.html accessed 11.07.2014. 24 Haseeb Uz Zaman, Tahir Saleem, Azhar Shehzad, Mohsin Ashfaq & Muhammad Bilal. 2011. Comparison of compressive strength of concrete calculated by destructive and non-destructive testing. Chapter 6. 18 Schmidt hammer is really a useful handy technique but can’t be really relied upon. It is a test which requires personal competence. The values of the test are quite variable even when same test is performed on the same element at two different places. Reason for that is the nature of the test. As described earlier that rebound hammer calculates the surface hardness of the concrete which then we relate to the compressive strength with empirical charts/graphs. So if there will be an aggregate just beneath the surface of the test point then it will give high value and if there is a plane of weakness (cement paste in the fire damaged concrete is the weaker plane) then it will show less values. Moreover, the nature of the test and its requirement to interpret hammer value to the compressive strength summed up to deviation of 15% to 30%. Conditions of smooth surface and repeated number of tests at the same points and no of points required for successful testing make it very difficult to test the fire damaged concrete structures where concrete spalling and disintegration is often the case.25 2.4.2.2. Ultrasonic Pulse Velocity This is a commonly used non-destructive test. It is done to assess the quality and compressive strength of concrete by ultrasonic pulse velocity method. The method consists of measuring the time of travel of an ultrasonic pulse passing through the concrete being tested. Comparatively higher velocity is obtained when concrete quality is good in terms of density, uniformity and homogeneity etc. To evaluate the compressive strength of concrete we use graphical relationship between pulse velocity and compressive strength of concrete.26 The functioning principal of ultrasonic pulse velocity is entirely different from Schmidt Hammer. A pulse of longitudinal vibrations is produced by an electroacoustical transducer, which is held in contact with one surface of the concrete under test. When the pulse generated is transmitted into the concrete from the transducer using a liquid coupling material such as grease or cellulose paste, it 25http://www.concrete.org.uk/fingertips_nuggets.asp?cmd=display&id=893 accessed 11.07.14. Haseeb Uz Zaman, Tahir Saleem, Azhar Shehzad, Mohsin Ashfaq & Muhammad Bilal. 2011. Comparison of compressive strength of concrete calculated by destructive and non-destructive testing. Chapter 7. 26 19 undergoes multiple reflections at the boundaries of the different material phases within the concrete. A complex system of stress waves develops, which include both longitudinal and shear waves, and propagates through the concrete. The first waves to reach the receiving transducer are the longitudinal waves, which are converted into an electrical signal by a second transducer. Electronic timing circuits enable the transit time T of the pulse to be measured.27 Ultrasonic pulse velocity is a good technique for examining concrete but it has its limitations as other non-destructive testing methods. This testing technique measures the propagation time of waves through the concrete in reality and there is no direct relation of wave propagation timing and concrete’s strength but some indirect relations are used to get concrete’s strength. Hence, possibility of error and deviation from result is there due to the conversions involved28. Moreover, it indicates the level of cracking in the structure with the fluctuation of the propagation time of wave within set distance not the concrete’s strength. Although concrete’s strength is then calculated by indirect relations.29 Moreover specific care has to be taken while conducting ultrasonic pulse velocity tests. Experienced testing staff are required as this test depends upon the competence of the inspector’s technical skills of getting the results and then the conversion of data to compressive strength. Several factors have their say in the end results for example  Temperature of concrete If the temperature of concrete is between 0 degree to 40 degree Celsius, then we can get right results otherwise if temperature is above 40 or below 0 then the deviation will occur and respective corrections have to be implemented.  27 Moisture level Haseeb Uz Zaman, Tahir Saleem, Azhar Shehzad, Mohsin Ashfaq & Muhammad Bilal. 2011. Comparison of compressive strength of concrete calculated by destructive and non-destructive testing. Chapter 7. 28 From pulse velocity to strength through graphs and formulas. 29 Haseeb Uz Zaman, Tahir Saleem, Azhar Shehzad, Mohsin Ashfaq & Muhammad Bilal. 2011. Comparison of compressive strength of concrete calculated by destructive and non-destructive testing. Chapter 7. 20 If moisture level of concrete is more than usual then it will also cause deviation in readings as waves propagates through water filled pockets in concrete faster than the dry air filled concrete. Therefore, structure, that is not dried after it became wet due to the water sprayed over it due to firefighting, cannot be accurately assessed. Usually, there is a difference of 2% is there which can be adjusted.  Surface of testing Surface on which transducers are placed must be smooth and if it is not then it must be prepared by grinding and then by applying wax to tightly put transducers against the surface of concrete. As in case of fire damaged building where excessive spalling is experienced, there this methodology can’t give the right impression about the concrete. In these cases spalled layer of concrete can be removed then tests can be performed.  Effect of reinforcement The propagation travelling time through the reinforcement bar is almost twice as of concrete hence if the reinforcement bar is along the length of the testing points then tests can’t be relied upon. This Puts a serious question marks on the application and utility of test. All these limitations of this testing technique doesn’t let this NDT technique to qualify as a reliable testing technique for the evaluation of the fire damaged concrete structure but still can give valuable input if properly conducted with care to its sensitivities and results are properly adjusted for respective deviations.30 2.4.2.3. Windsor-Probe or Penetration Resistance test Windsor probe or penetration resistance test is used as a non-destructive testing technique for the evaluation of concrete’s compressive strength. The nature of test doesn’t gives accurate evaluation of compressive strength because of the properties and nature of the method. The equipment as shown in the figure below consists of the gun-powder actuated driver and a steel alloy probe. The probe is pushed into the concrete by the measured amount of energy supplied to it by the explosion of gun powder in the cartridge. The depth upto which the probe 30 CPWD, India. 2002, Handbook of repair and rehabilitation of R.C.C buildings, page no III-20. 21 penetrates into the concrete is related to the strength of concrete by the help of empirical relationship. The results are usually not much disturbed due to the moisture content or concrete texture but care has to be taken in term of surface preparation and minimum dimensions of the test subject. Limitations states that minimum edge distance and member thickness should be 150 mm. Moreover the presence of reinforcement direct under the probe or in the vicinity of 50 mm will obviously be a problem and will give misleading reading hence have to be avoided.31 Figure 3: Penetration Resistance32 The accuracy of the test depends upon the correlation used to relate probe penetration with the compressive strength of concrete. The correlation is provided by the manufacturer for specific type of aggregate and concrete mix used because. It is sensitive to the aggregate hardness unlike crushing test of concrete cubes. For concrete of same strength measured by crushing test of concrete cubes, penetration resistance test can give different values of strength if one has harder aggregate and the other one has softer. Hence the charts or correlation provided is for a specific aggregate concrete because it is prepared by the tests on concrete with specific aggregate in the laboratory.33 Windsor probe test can be employed for the evaluation of the fire damaged concrete structure but again inherits the limitations associated to non-destructive testing techniques. It is sensitive to the aggregate used in concrete hence 31 V.M. Malhotra, Nicholas J. Carino. 2004. Handbook on Nondestructive Testing of Concrete Second Edition. Page no 2-4. 32 CPWD, India. 2002, Handbook of repair and rehabilitation of R.C.C buildings, page no III-23. 33 CPWD, India. 2002, Handbook of repair and rehabilitation of R.C.C buildings, page no III-24. 22 comprehensive information of the concrete mix and aggregate used in the concrete of the structure must be available to get results with better accuracy. Because only then that kind of concrete mix with same aggregate can be recasted in cubes and these cubes can be then used to formulate the correlation between penetration of probe and the compressive strength of concrete. Another way to use this testing technique is for the comparison of undamaged concrete and fire damaged concrete of the same building. The penetration depth of probe will be obviously different for damaged and undamaged concrete and as both concrete are of the same structure and most probably will be having same concrete mix and aggregate. Hence the information of the concrete is valuable for employing penetration resistance test for accessing concrete compressive strength. Penetration resistance test is not sensitive to the personal skills though probe has to be at right angle to the testing surface and it is compulsory but doesn’t require special skills to be carried out. Surface of the testing subject has to be smooth for the test to be conducted. In case of fire damaged concrete which has spalled has to be prepared for the test first. The general level of accuracy of results in penetration resistance test is considered to be around 20% when compared to the actual compressive strength obtained by crushing cube test. Hence penetration resistance test can give valuable input but once again can’t be completely relied upon especially if right correlation can’t be obtained and structure is completely burnt out and no same concrete is available in the structure for comparison purpose.34 2.4.2.4. Core Sampling and Testing Core sampling and testing is one of the most trusted techniques used as nondestructive testing technique. Actually it is partially destructive testing technique. Core sampling and testing is pretty much reliable if properly conducted and conditions fulfilled. In core sampling, the core is cut by rotary cutting tool with industrial diamond bits at its tip. Concrete core is obtained and then taken to laboratory for testing. Concrete cores size (diameter) is not specified but minimum criteria is the diameter of the core must be 3.5 times the maximum size 34 CPWD, India. 2002, Handbook of repair and rehabilitation of R.C.C buildings, page no III-24. 23 of aggregate. The length to diameter ratio of the core that is used to measure compressive strength must be between 1 to 2, most preferable between 1 to 1.2. Before testing core can be trimmed to the length satisfying the above criteria of length to diameter ratio with the help of diamond saw.35 Core cutter test is not limited to the measurement of compressive strength measurement but also helpful in measuring the depth of concrete damaged due to fire. It also reveals other construction flaws like honey combing due to poor compaction that could possibly be there and would be responsible for poor strengths calculated by NDTs instead of the damage endured by fire. These cores obtained are also used in petrography (discussed later). Figure 4: Core obtained by drilling36 Core obtained by drilling don’t have smooth ends moreover due to fire there may be some spalling and rough texture so it is important to smooth these regularities up and made end parallel and smooth. Usually it is done by capping. Material used for capping is high aluminium cement or sulphur sand mix. During obtaining core samples special care has to be taken into account so that there wouldn’t be any damage to core (usually it happens). Then these cores are tested in compressive strength measuring machine by loading them upto crushing hence compressive strengths are measured.37 Core sampling and testing is a reliable technique to evaluate the condition of concrete and acts as the final piece of the assessment by NDT puzzle. It is 35 CPWD, India. 2002, Handbook of repair and rehabilitation of R.C.C buildings, page no III-28. http://www.cctia.org/FAQ_Files/10.001_Concrete_Core_Tests.html accessed 21.07.2014. 37 CPWD, India. 2002, Handbook of repair and rehabilitation of R.C.C buildings, page no III-29. 36 24 sensitive to some factors majorly the geometry and dimensions of the core and lack of standardization. But the results are fairly accurate for normal and standard core sizes in normal practice. Core’s compressive strength obtained from good concrete and from damaged concrete from same structure or even different ones can be compared in order to evaluate the damage done by fire. 2.4.2.5. Deflection measurement with digital theodolite Fire cause sometimes permanent deformations within the reinforced concrete elements. If the temperature of reinforcement reach above their specified limits and then there is some permanent set in them after it is cooled down. Loss of strength and cross sectional area causes extra deflections in flexural members like beams and slab elements. Flexural members are deflected in nature to some extent already under the sustained loads before the event of fire as well but the deflections are not huge in general and mostly not even detectable. After serious fire, significant deflections are observed mainly due to the elongation or other kind of change in properties of reinforcements. These deflections can be measured with the help of Digital Theodolite upto the precision of 1 sec. Hence deflections of these flexural members are quite helpful for the understanding of the condition of reinforcements in the R.C.C structural elements.38 2.4.3. Laboratory testing Investigation of the fire damaged structure started by the means of desk study, where general knowledge about fire and structure was studied. After desk study, visual inspection is carried out to witness the damage and to have some idea about the nature, and extent of damage. Visual inspection and inspection of debris is concluded to understand the fire behaviour and properties like if aluminium frames of windows are melted then it means that the temperature of fire would be around 500 Celsius. After visual inspection of the building’s 38 Ivan Detchev, Ayman Habib, Mamdouh El-Badry. 2011. Case study of beam deformation monitoring using conventional close range photogrammetry. Page no 1. 25 structural and non-structural parts condition assessment with field and laboratory testing can be conducted as damage is located during visual inspection part. The field test mainly consisting of NDTs and partially destructive testing like core sampling. These NDTs mainly gives quantitative idea about the residual strengths of the structural members. The results obtained from NDTs can exhibit accuracy upto 80% with 20% margin of disturbance (which is still a lot). If that is what is required then further delicate laboratory testing techniques like Petrography, Differential thermal analysis and Thermo gravimetric analysis (TGA) and Fire modelling Techniques are not required. But if exact nature, extent and depth of damage is required to be evaluated then following laboratory techniques will do the rest of job. In case of fire damaged buildings, Petrography test is the ideal test and give what is needed. Other Techniques like DTA and TGA wouldn’t be discussed, as they are not usually required or feasible to be carried out. 2.4.3.1. Petrography Petrography test is like putting the structure under microscope, literally. Petrography is actually a geological technique that is employed in civil engineering in which small prepared samples of concrete are studied under different microscopes (including polarized light, or petrographic microscopes and scanning electron microscopes). In this test chemical and mineralogical studies of concrete samples are conducted. 39 Petrographic test are conducted for understanding the cause of failure, condition assessment of damaged structure due to known cause like fire or freeze thaw cycles etc. Petrographic testing can define a range of parameters that can exactly evaluate the fire damaged building. Some of the common parameters that can be investigated by Petrography are as under40   39 Grading, Type, condition, colour and shape of aggregate Nature of cement paste including the addition of admixture. Laura J. Powers. 2002. Petrography as a Concrete Repair Tool. Page no 22. accessed 25.07.14. 40http://www.concrete.org.uk/fingertips_nuggets.asp?cmd=display&id=575   26 Presence of impurities and air voids in concrete  Bond between aggregate and cement paste  cycles and Alkali-silica attack and carbonation depth. Information about the chemical attacks, sulphate attack, freeze thaw Depth of fire damage and temperature of fire41 Petrography is done on the samples that are obtained from the field by core sampling at various depths. These samples are then treated with proper surface treatments like polishing or thin sectioning to prepare them for testing. Thin sections are prepared of the thickness one quarter of the hair to study it under petrographic microscope. The sample must be extracted with care as it must inhibit the characteristics of the damage that is needed to be studied. Moreover information of the concrete mix is also helpful like water cement ratio, concrete mix and minimum air content. As here we are only interested in fire damaged buildings so limiting petrography’s utility for fire damaged buildings. Petrography can investigate about the condition and colour of aggregate. It can also investigate about the bonding between aggregate and cement paste moreover can study the crack pattern in cement paste. All these inherent properties of Petrography makes it a handy tool for the investigation of fire damaged building. As it is an established fact that at high temperature there are chemical and physical changes in the material ingredients of concrete. Aggregate colour changes, changes in the crystals of materials, crack pattern and bonding between aggregate and paste all occurs at high temperatures. These changes can be identified by Petrography and then the data obtained is used to do fire analysis and to determine the depth of damage as well as the temperature of fire. The colour changes and pattern of cracking and crystal pattern are observed to determine the temperature that concrete has attained. Following figure sheds some light over the fact, that how Petrography can be employed to determine the condition of the concrete and to understand the temperature of concrete under the event of fire. 41 http://www.concrete.org.uk/fingertips_nuggets.asp?cmd=display&id=575 accessed 25.07.14. 27 Figure 5: Colour of aggregate in Petrography test 2.4.3.2. 42 43 Tensile Test After concrete, reinforcements are tested in order to identify their residual strength and evaluate the extent of damage it has endured in the unfaithful event. If concrete cover is not thick and spalling of cover has occurred then there are fair chances that reinforcement bars will be damaged. To measure that tensile test is performed on piece of reinforcement bar extracted from the fire damaged structure. These reinforcement bars are first cleaned and made clear form any concrete of cement attached to it then it is tested until failure in UTM. Figure 6: Universal testing Machine for tensile test44 The samples are placed within the grips of the UTM and then they are loaded under uniform tensile load until failure. The reinforcement bar piece will be 42 Laura J. Powers. 2002. Petrography as a Concrete Repair Tool. Page no 23 Colour of aggregate shows that the temperature attained by the concrete was from 570 to 1100 Celsius. This is the temperature at which colour changes from Pink to Brick red. 44 http://www.engineeringarchives.com/les_mom_tensiletest.html accessed 26.07.2014 43 28 elongated in the centre. In case of ductile failure it will show necking and in case of brittle failure it will not show any necking as shown in the next figure. The data is obtained and inform us about the ultimate load, ultimate stress, maximum elongation and reduction in area. Form these data other important information like yield strength and Young’s modulus can be obtained. Hence Tensile Test gives us virtually all necessary information we require about the reinforcements of the fire damaged concrete structure. The effectiveness of tensile test is more important in the sense that it doesn’t calculate the strength by any indirect measure but actually gives the original residual strength of the damaged reinforcement bars. 2.4.3.3. Scanning Electron Microscopy (SEM) SEM test is conducted on the damaged reinforcement specimens to understand the patterns of the material fibre, which gives valuable information about the stress in the reinforcement bars. Especially in case of pre stress concrete members, this technique is useful to understand the residual tensile stress in the pre stressed reinforcement (HS strands). This is pretty helpful in term to understand the overall stability and integrity of pre-stressed concrete elements. Summary Fire damages the building and the extent of damage depends upon temperature and duration of fire, Conditions of fire (e.g. air ventilation), building materials, location of fire (basement, top floor, etc.), quality of design and construction and load sustained by building. After the fire, building structure must be secured first and building must be cleared by respective authorities for further investigation. Building is consisted of various materials (concrete, steel, glass, aluminium, other metals, timber etc.). Each material has its unique behaviour when exposed to fire and elevated temperature, which depends upon their nature, 29 physical and chemical properties. Concrete is an inert material and virtually incombustible. It is classified as A1 category material by European classification system of building material. Concrete undergoes different physical changes when its temperature rises. At 300 C, due to the oxidation of aggregates present in the concrete, it changes its colour to pink. This is considered as the indication that concrete has undergone significant loss of strength. After fire, reinforcing steel retains its strength significantly upto 450 C in case of cold rolled steel and 600 C in case of hot rolled steel. Under these limits it can be reused. Pre-stressing steel loses significant strength at 200 C to 400 C. At 400 C, it loses 50% of its strength. Hence more sensitive to fire. Before continuing to the building’s condition assessment, homework about the case object has to be done which includes desk study of building structure, type of building and construction materials, floor area damaged, scope of damage, general information about the building, size and duration of fire etc. Building documents like blue prints and fire report from fire or police department can be used for the task. Condition survey (visual assessment) of utilities and non-structural members can be quick and decisive as usually building inspectors don’t need further testing to understand their condition. Visual inspection of debris provides with important information about the fire. For structural members both condition survey (visual inspection) and condition assessment (field and laboratory tests) are required to exactly establish the residual strength and stability of structure. Non-destructive testing is the main technique employed in field testing. Schmidt hammer, ultra-sonic pulse velocity, Windsor-probe test, Ground penetration radars, laser scanners and thermography all are used. But according to their nature and feasibility usually first three are practical for buildings. These all three tests don’t give accurate idea about the concrete’s condition and structure’s health due to their nature and technique. Schmidt hammer doesn’t measure the compressive strength directly but infact measures surface hardness, which is then used to estimate compressive strength with the help of empirical correlations. Ultrasonic pulse velocity test 30 measures the velocity of pulse between set distance of two transducers. It doesn’t measure the compressive strength directly either and obtains it by correlation as well. Use of these techniques over spalled concrete surface which is usually the case of fire damaged buildings is difficult and sometimes not even practical. Windsor-probe test indicated about the residual strength of concrete by penetrating probe into the concrete and measuring the length that is left outside of concrete. It is very sensitive to the aggregates used in concrete mix and requires aggregate information for relative precision. All these NDTs for evaluation of concrete doesn’t give accurate results and hence must be supported by core test which is comprehensively reliable but partially destructive. If core sampling and testing is done with care and required conditions are fulfilled then, it can give reliable information about concrete and structure. Hence, if possible then, must be given first preference over all other field tests for the evaluation of concrete and damage done. For assessing condition of steel in flexural members digital theodolite is used to measure deflections. If field test, which usually are not very accurate, are not enough and higher level of accuracy is required then laboratory tests like Petrography for concrete and tensile test and Scanning electron microscopy for reinforcements are done. Petrography is a complete test as it gives approximately all kind of information that is required to access condition of concrete in fire damaged concrete buildings. Techniques like DTA and TGA are not required or even feasible sometimes after Petrography. So collectively in authors opinion, core sampling and testing combined with Petrography are sufficient to evaluate concrete in case of fire damaged concrete building. But to jump for these testing techniques in every case of fire damage is not advisable. For light to moderate damages simple visual inspection and NDT testing may be sufficient enough. 31 3. Rehabilitation and Retrofitting of fire damaged building After it is established that rehabilitation of the building and retrofitting of the structure is feasible both on technical and financial grounds, rehab of the building will be started. While discussing the rehabilitation and retrofitting of the building, various options pops up. Each option has its own properties, feasibilities and therefore shortcomings too. Similarly every case is a unique case as well and has its own requirements. In some buildings. We have the luxury to consider different solutions and select from them but sometimes this is not possible due to some restricting factor like services of the building doesn’t permit that. For fire damaged building not many options are available for retrofitting of structure. Most conventional ones are strengthening of structural members with fibre reinforced plastic and replacement of damaged concrete either with shotcrete or in-situ placement of concrete. These are quite commonly practiced and may not be very suitable in every case. Some new methods for retrofitting of fire damaged structures will also be discussed that are not common for such cases like steel jacketing, concrete jacketing or provision of extra members. These measures are usually used for other purposes like protection against earth quakes but if chosen after careful analysis then may prove to be beneficial in comparison to other more conventional measures. Different rehabilitation and retrofitting measures will be presented in this chapter with their respective mechanism, feasibility, pros and cons etc. These measures will then be assessed for various factors like sustainability, insurance factor, safety etc. Hence at the end, it will provide help for designers to choose from the solutions presented in the document according to the unique demands of the building and specific goals of the project. 3.1. Cleaning Just after the fire building is in filthy condition, depending upon the size, nature and duration of fire. It is better to clean the building and secure the residual stuff 32 as soon as possible after building is cleared to be safe by the police or fire department. It will minimize the impact of damage and make it easier and cost efficient to recover the building and belongings. Water or fire extinguishing foam is used to extinguish the fire. Therefore, the only worrying point is not fire and smoke damage but possible water damage as well. This measure must be taken preferably just after the fire even before assessment and evaluation and decision making phase. This will not allow the soot and smoke deposits or penetrate inside and further damage will be prevented as the acidic fumes and particles in smoke and soot will not be granted enough time to inflict damage.45 In the beginning all water accumulated in the building must be removed by the help of pumps and manual equipment. Fire extinguishing foam is removed as well from the building. It is very important to dry the wet surface as it will otherwise generates the problem of mold. High ventilation in the building is highly recommended and if possible or required then dehumidifiers can be used. Professional cleaners are required for cleaning job in case of heavy fires.46 Heavy soot47 will be deposited on the accessories and the building structure. It is important to deal with it properly and remove it from the surface otherwise it will deteriorate them and the smoke smell will become a permanent stay in the facility. Inspection of building services like HVAC is important. All such building services or property that has been damaged beyond repair should be identified in the beginning and disposed properly. For the remaining belongings and building structure can then be subjected to cleaning and repair works. There are various techniques to deal with soot deposited on different surfaces. For curtains and upholstery (furniture), it is preferred to use vacuum cleaners before washing them. It is necessary to uplift soot with the nozzle of appropriates vacuum cleaner before washing otherwise soot will penetrate into the fabric. Soot have to be removed from the walls and ceiling as well with the help of chemical 45 Institute of Food and Agricultural Sciences, University of Florida. 1998. The Disaster Handbook National Edition. Section (13.17). Page no 1. 46 Institute of Food and Agricultural Sciences, University of Florida. 1998. The Disaster Handbook National Edition. Section (13.17). Page no 2. 47 Soot is the oil that evaporates during the fire from the materials that are burnt. 33 sponge and if required then some counter chemicals can be used. If soot is not properly removed from the surface of walls and ceiling then the smell of fire wouldn’t go away.48 Figure 7: Soot cleaning from Ceiling49 3.2. Removal of smoke odour Smoke penetrates the building in the event of fire. The smoke is very problematic in case of fire. Smoke penetrates virtually through very other material present in the building. It persists in the building if not properly removed. Records recovered from 1906 San Francisco fire that are currently stored in National Achieves of USA, still have very strong odour of smoke. It can give the idea that how critical this problem is. To understand the gravity of the problem first it is necessary to understand smoke and its composition. Smoke is the combination of gases, liquid and solid fumes that emits from the fuel. They are considered as the unburnt part of the fuel and they may contains toxic and carcinogenic particles. The size of these particles is less than 10 microns in diameter, mostly they are less than 1 micron. Hence it is critical to get rid of smoke particles as they pose serious health issue and sometimes acidic fumes that may contain corrodes and damages the property and structure like wise.50 48 Department of Public health, Los Angeles County. 2013. How to clean up smoke and soot from a fire. Page # 2. 49 http://www.ccwonline.com.au/prod437.htm accessed 11.08.2014. 50 http://chicora.org/fire.html accessed 11.08.2014. 34 Thermal insulation can significant capacity to store smoke particles and retain it for long time. If there is any such insulation in contact with smoke then it’s better to replace it otherwise dry cleaning and treatment with counter chemicals will take care of the problem to some extent. Thermal insulations at attic are mostly damaged in case of fire if there are any. It is better to replace the insulation with new one. Smoke that has penetrated the ducts can be sealed on the walls of the ducts with the help of chemical sealers as it is very difficult to access the inner side of these ducts.51 For the rest of the building and its belongings thermal foggers, ozone machines and air scrubbers are used. Aerosol sprays or deodorisers can’t cover the smoke smell for long and sometimes they mix with the smoke and creates a new smell that might be more irritating. Thermal foggers creates a fog from water based masking agent. It super heats the masking agent that produces the fog. Fog then travels through the building and its properties just like smoke and reaches where smoke might have reached. Thermal foggers comprehensively deals with the smoke but it has its disadvantages too. The material that has already been under stress from fire and smoke is then again subjected to the high temperature fog to ward off smell. It puts extra stress over the material of property.52 Ozone machines produces ozone in large quantities. Ozone roams through the building and disinfect the building. The problem associated with ozone treatment is serious though as ozone is a strong oxidizing agent and oxidize virtually all organic matter. Due to ozone treatment, leather will be damaged. It embrittles paper, inks and dyes will be faded, and if concrete spalling is extensive then it will reacted to the exposed steel surface to make metallic oxide. Moreover ozone causes irritation in eyes, lungs and skin. Hence its application is very limited and should not be used everywhere as it virtually ages every material in household. 53 51 Institute of Food and Agricultural Sciences, University of Florida. 1998. The Disaster Handbook National Edition. Section (13.17). Page no 4. 52 http://chicora.org/fire.html accessed 11.08.2014. 53 http://chicora.org/fire.html accessed 11.08.2014. 35 Figure 8: Thermal fogger (A), Ozone Machine (B) 54, 55 Air scrubbers are used to depollute the particles and fumes from the air. Smoke particles that are suspended in the air or trapped in the corners will be removed with the help of air scrubbers. Special air scrubbers are used for smoke damage that cycles air 5 to 6 times in an hour. After repeated cycles the air is pollutant free and smoke particles are arrested by it.56 Figure 9: Air Scrubber57 3.3. Rehabilitation of non-structural members and utilities During fire, non-structural members and utilities undergoes more damage than structural members. Thanks to the inherent properties of concrete and steel that 54http://www.agi.my/index.php/our-solutions/disaster-restoration/a-restoration-services- include/stubborn-unpleasant-odor/thermal-and-mist-treatment-to-remove-all-types-of-malodor/ accessed 11.08.2014. 55 http://www.cleanfax.com/articles/105969-effective-thermal-fogging accessed 11.08.2014. 56 http://www.wisegeek.com/what-is-an-air-scrubber.htm accessed 11.08.2014. 57 http://www.emssales.net/store/cart.php?m=product_detail&slug=predator-600-portable-airscrubber. (accessed 11.08.2014.) 36 makes them inert even on high temperature and provides necessary fire proof properties up till sufficient temperature. Fire damage is quite serious in case of materials made up of combustible material like plastics, fibre plastics, wood etc. and these are the materials that are usually used for non-structural members and utilities. Commonly, HVAC ducts are made from plastics and fibre plastics not only get damaged but infact increases the fire load. Utilities like HVAC, if decided to be repaired after feasibility studies then they would be restored but usually that’s only the case of partial destruction. If they have endured heavy damage then it is usually better to restore them. Special attention can be provided towards the improvement of already existing systems. Challenges sometimes are there from the provisions and code requirements. Sometimes building design doesn’t support the changes and actual material for replacement is not available in market or have to be exported from somewhere else which cost too much time or money. Non-structural members like façade, partition walls, suspended ceiling etc. bears heavy damage as well and again their damage depends upon the material of their composition. Glass façade usually gets heavy damage where it gets in contact with the direct flames and usually glass is broken within 30 minutes. Glass façade provides safety issues as they retains gases and smoke inside the building because of lack of sufficient openings which markedly increases the causalities in fire incident. Glass panels that are damaged has to be replaced with similar ones and rest of the damaged glass tiles can be rehabilitated just by cleaning. Other façade materials like metallic sheets, terracotta, marble tiles, brick tiles etc. doesn’t suffer heavy damage and usually just few tiles that would be in direct access of high temperatures are required to be replaced. Otherwise, cleaning job will take care of the rest of the job. Sometimes it is required to use Soda-blasting technique to remove the accumulated soot and smoke over the surface. Soda blasting is a very handy technique in which Sodium bicarbonate particles that are very fragile in nature are bombarded over the surface from an air pressured nozzle just like paint job for vehicles. These small particles struck the surface and explodes into smaller particles and takes the coating soot or rust or smoke with 37 them, leaving clear undamaged original surface beneath. Soda also spreads over the surface and deodorize the surface from smoke smell.58 Figure 10: Soda-blasting59 Walls, like façade also depends upon the material of construction. In case of brick of concrete walls, damage is not significant as both have good resistibility. The damaged part of plaster or concrete can be removed and repair is provided with new concrete and plaster but usually it is not required. Surface treatment of roughness and spalled concrete is provided. Afterwards soda-blasting is done to remove smoke and soot deposited on the surface. Partition walls are sometimes need removal of partitioning boards and repair of wooden frame. If wooden frame is deeply damaged then it is better to replace it. For plaster boards once again soda blasting will provide fitting solution to get rid from fire stains and odour. Same goes for suspended ceilings. Those panels that are too much damaged are replaced otherwise they are cleaned with soda blasting. 3.4. Retrofitting of structural members Structure is the skeleton of the building. It provides the integrity, strength and stability to the building to perform its function. Structural safety is one of the outmost important thing. During fire, building’s structure resists the fire and counters it upto a certain point according to its fire rating. If structure is loaded during fire as well then it reduces the material capacity of fire resistance. Under 58 59 http://www.escablast.com/store.asp?pid=35117 accessed 12.08.2014. http://cleanerscoach.com/Media-Blasting.html accessed 12.08.2014. 38 fire structure shouldn’t fail, which would ultimately cause the demolition of the whole building. Concrete structures have proven to be very stable in fire especially when compared to wood and steel structures, all thanks to the superior fire resistant properties of concrete. In the event of fire R.C.C members endured damage due to high temperature but this is not the only worrying point when it comes to retrofitting of structure. After fire , use of water to extinguish the fire or fire retardant foam cause sudden cooling of structure that have been at very high temperatures this causes permanent set of deformation, cracking and spalling. Structural Retrofitting is the process of structural repair by which original strength of structure is installed or increased so that it can fulfil its intended function successfully and safely. Various methods of structural retrofitting has been under practice but it lacks innovation as it is in whole construction industry. Recent most innovation in retrofitting techniques is the use of fibre reinforced plastic dates decades ago. Most conventional system of structural retrofitting will be discussed in this section with their relative advantages, disadvantages, opportunities and short comings. 3.4.1. Fibre Reinforced polymer (FRP) Fibre reinforced polymer is a synthetic material in which polymer matrix is reinforced with fibres. Most commonly used fibres are glass, carbon or aramid though other fibres are also used in FRP. FRP is light in weight, exhibits high strength and stiffness. It is non corrosive as well. These inherent properties of FRP makes it a suitable candidates for repair work. It is possible to repair a heavily damaged structure with fibre reinforced plastic. FRP is used in number of forms for structural strengthening. FRP plates and thin sheets are commonly practiced though new research is going on FRP bars that can replace steel bars in structures. The efficiency of FRP repairs is based upon number of factors. At first the properties of the FRP material are important. The kind of fibres which are used in the polymer matrix defines the material properties and hence plays a crucial role overall. FRP sheets are actually weak in shear in transverse direction and the orientation of the fibre with respect to the element remains critical as well. 39 Hence FRP sheets are wrapped in such a way that the direction of the fibres is perpendicular to the longitudinal axis of the element or to the axis along which element requires flexural stiffness.60 Another factor that plays very important role in the overall success of repair and instalment of strength and stiffness is the method of application. For different members the method of application of FRP sheets or straps is different which will be described in detail later in the topic. Last but not least epoxy resins that are used as glue for the application of FRP wraps over the damaged structural member is of prime importance. Some researches even states that it is the telling factor for the successful restoration of the strength. Surface of damaged member should be prepared before the application of the FRP straps. Any irregularity that may cause rupture in the FRP sheets must be taken care of by grouting or resin injections. Sharp edges of non-circular members must be rounded by grinding machine. All these measures are important because FRP material is prone to rupture and it dramatically changes the behaviour and scenario of strength reinstalment. After preparing the surface of concrete epoxy resins are applied to the surface and on the wraps as per requirements and then applied to the structural members immediately and some pressure is applied over it to squeeze out the extra strength from bonding. Hence application of FRP over the damaged structure should be properly monitored for above mentioned factors.61 Various researches have been conducted to estimate the impact of FRP treatment over the strength and over all structural revitalization. It has been established through experimental research that FRP treatment increases both compressive and flexural strength. It also provides extra confinement to the elements which is handy for better shear resistance and stiffness. For M25 grade concrete, increase in compressive strength is 67%, 129% and 150% for one, two and three layers of GFRP sheet wrapped around concrete.62 Martin Alberto Masuelli. 2013. Introduction of Fibre-Reinforced Polymers – Polymers and Composites: Concepts, Properties and Processes. Page no 29-31. 61 Martin Alberto Masuelli. 2013. Introduction of Fibre-Reinforced Polymers – Polymers and Composites: Concepts, Properties and Processes. Page no 29-31. 62 Ponmalar. 2012. Strength comparison of Fiber Reinforced Polymer (FRP) wrapped concrete exposed to high temperature. Page no 150. 60 40 Beams are repaired by two ways. One is by applying FRP plates on the tension side of the beam which is on the downwards side in the middle of supports. Alternatively beams are wrapped on three sides by FRP wrapping sheet making a U and additional protective layers are provided along the axis of beam as shown in the figure below. For application of FRP material usually epoxy resins are used but sometimes steel bolts are also provided but it should be monitored that they don’t provide a weaker plane in cross section.63 Figure 11: FRP plate application beneath the beam64 Figure 12: FRP Wraps on side faces and bottom side65 For column repairs, FRP wrapping sheet material is used. The surface is prepared and FRP sheet are wrapped around the column with epoxy resins. The Martin Alberto Masuelli. 2013. Introduction of Fibre-Reinforced Polymers – Polymers and Composites: Concepts, Properties and Processes. Page no 29-31. 64 http://www.frpbeam.com/ accessed on 14.08.2014. 65http://www.bow-ingenieure.de/HTML_deutsch/03_projekte/30_projektseiten/1998078_CFK_Lamellen/1998-078_CFK_Lamellen_engl.htm accessed 15.08.2014. 63 41 FRP sheets are slightly overlapping with each other. Number of sheets used for the repair is dependent upon the design and degree of damage member has endured during the infortune event. The confinement provided by the FRP wraps provides the stiffness and enhanced flexural strength along with better compressive strength. There are two methods to apply the FRP wraps. Applying wraps with pre tensioning and filling of grout between member and the FRP wrapping sheet. Second method is to apply FRP wraps in passive mode in which counter stress is produced for confinement when concrete column is subjected to expansion under the action of loads. The direction of fibres in the FRP is kept perpendicular to the longitudinal axis of column.66 Figure 13: FRP sheets wrapped around the Column67 For slab repairs, FRP sheets are pasted on the tension side of the slab so provide extra flexural strength to the element. FRP wraps are also provided to increase the shear capacity of the slabs where it has been damaged due to fire. FRP wraps are applied to the slab elements just as for beams. Usually the FRP sheet are wrapped with the help of epoxy resins, and mechanical fixings. Figure 14: FRP sheet wrapped on the tension side of fire damaged slab 68 66 Martin Alberto Masuelli. 2013. Introduction of Fibre-Reinforced Polymers. Page no 29-31 67http://compositesmanufacturingmagazine.com/2010/08/pursuit-newfrp-protection-heats/ accessed 15.08.2014. 68 Fay Engineering. 2003. KBP Coil Coaters Fire Repair and Shear Strengthening. Ppt. 42 FRP reinforcing is a very useful technique for rehabilitation of fire damaged building but choice of selecting FRP reinforcing material for retrofitting of structural members totally dependent on its material properties. We will discuss these properties one by one starting with pros and then coming towards cons.  FRP material is atleast 5 to 6 times more costly than steel on cost/unit weight or cost/unit length basis. But irrespective of the material cost that is many folds higher than the steel reinforcement, overall cost of the FRP is lesser than or atleast competitive to additional benefits. Most prominent benefits are costs of handling, transportation and labour. They are significantly lower than steel. Moreover, as described earlier that FRP is a non-corrosive material hence doesn’t need repairs as much it is required in case of steel. Though it require fire protection  because of its poor fire performance but still in life cycle costing.69  material hence not suspected to oxidation like steel.70 FRP is highly durable material if properly handled. It is a non-corrosive The material is light in weight in comparison to the steel and hence doesn’t add up excessive dead loads over the structure and easy to  handle which is quite useful feature of a repair material.71  FRP exhibits excellent tensile strength which is its strongest assert.72  some applications but generally it doesn’t really matter.73 FRP material is nonmagnetic in nature which can prove to be useful in FRP material doesn’t require special labour effort as it can be easily moulded into shapes and can covers almost all geometries of buildings without any formwork requirement. 74 69 Burgozne, Balafas. 2007. Why is FRP not a financial success?. Page no 1-9. Martin Alberto Masuelli. 2013. Introduction of Fibre-Reinforced Polymers – Composites: Concepts, Properties and Processes. Page no 1-5. 71 Martin Alberto Masuelli. 2013. Introduction of Fibre-Reinforced Polymers – Composites: Concepts, Properties and Processes. Page no 1-5. 72 Burgozne, Balafas. 2007. Why is FRP not a financial success?. Page no 1-9. 73 Martin Alberto Masuelli. 2013. Introduction of Fibre-Reinforced Polymers – Composites: Concepts, Properties and Processes. Page no 1-5. 74 Martin Alberto Masuelli. 2013. Introduction of Fibre-Reinforced Polymers – Composites: Concepts, Properties and Processes. Page no 1-5. 70 Polymers and Polymers and Polymers and Polymers and  43 FRP material is light in weight that is one of its many qualities but this is a double edge sword as it also not as good in stiffness as its challenger steel. This lack of satisfactory stiffness is responsible for heavy deflection which is not very appreciated. For example how many of us would like to sit under a heavily deflected beam. So although FRP proves to be a good repair material for fire damaged building but still it  doesn’t take cares of heavy deflection. FRP lacks shear strength or ability to resist shear stress in transverse direction. This inherent disability is another shortcoming attached to  use this material for beams where we may possibility of dowel action.75 FRP sheets are prone to wear and tear76. It can be ruptured due to any sharp object pointing force through it that’s why corners of non-circular  column are rounded prior to the application FRP over them. The FRP sheets as damage repair solution does one serious shortcoming. The failure action of FRP is brittle77. The mode of failure makes it dangerous. The structural elements are designed to have ductile failure by making it sure that concrete will fail at second and reinforcement first. Steel reinforcement has ductile failure. This assembly give the warning for the failure of structure. As concrete still have some capacity but steel have already shown plastic behaviour. Hence cracks will starts to appear on tension face. These cracks gives time to the habitants to evacuate. But a fire damaged element that is repaired with FRP will not have this luxury. As FRP will be completely wrapping it from all three visible sides (in case of beam) hence no cracks would be seen moreover FRP by itself has brittle mode of failure. Hence the structural element repaired with FRP will exhibit somehow brittle mode of failure which in turn means no significant warning although abnormal deflections may give indication but yet not sufficient. Martin Alberto Masuelli. 2013. Introduction of Fibre-Reinforced Polymers – Polymers and Composites: Concepts, Properties and Processes. Page no 1-5. 76 Martin Alberto Masuelli. 2013. Introduction of Fibre-Reinforced Polymers – Polymers and Composites: Concepts, Properties and Processes. Page no 1-5. 77 Martin Alberto Masuelli. 2013. Introduction of Fibre-Reinforced Polymers – Polymers and Composites: Concepts, Properties and Processes. Page no 1-5. 75  44 FRP shows poor performance when exposed to high temperature.78 This requires extra fire protection to the FRP reinforcing plus better fire  proofing for building as well. Environmental impact to FRP is a serious setback for this repair method as sustainability is an important issue. FRP material is not a green material as it depletes fossil fuels. Moreover acidification, air pollution and smog is related to its production. Moreover, it can be recycled to perform the same function as it is in case of timber or Steel. Hence on surface material resources, production process, energy requirements and environment pollution makes it a brown material or unsustainable material but in depth life cycle analysis raise some hope. Moreover whole demolition and reconstruction job is not sustainable either so we may raise a case that FRP repair is atleast greener than demolition and reconstruction. When we compare it with other measure of retrofitting then its sustainability may raise serious question over its superiority as a repair or retrofitting measure.79 3.4.2. Partial removal and replacement of concrete and reinforcement During fire, both concrete and steel undergoes damage. Degree of damage is assessed in condition assessment and survey. For retrofitting of the damaged structure it is mandatory to have clear ideas about the structural condition and its integrity because only then the methodology and requirement for this method can be decided. Basic idea behind this repair method is to remove the damaged concrete by some suitable mean (hydro blasting, Jack hammer etc.) upto the depth of damage. Then remove the part of reinforcement bar/bars that has/have been damaged (if any). Then preparation of surface for repair application. Usually the surface is Martin Alberto Masuelli. 2013. Introduction of Fibre-Reinforced Polymers – Polymers and Composites: Concepts, Properties and Processes. Page no 1-5. 79 Martin Alberto Masuelli. 2013. Introduction of Fibre-Reinforced Polymers – Polymers and Composites: Concepts, Properties and Processes. Page no 1-5. 78 45 prepared and good enough for repair application in case of concrete removal by hydro blasting. After concrete removal and preparation of surface reinforcement bars that have been removed are replaced by suitable means (overlapping or welding etc.)80. Then concrete is replaced by in-situ casting with the help of form work or by shotcrete such that it reinstate the original form and provides sufficient strength for structural requirements. The whole process is explained in detail below. 3.4.2.1. Removal of concrete In petrography test, the depth of concrete damage is determined. Moreover Core sampling provides information as well about the depth of damage. These two measures dictates the damage depth as well as reveals any other inherent defect that have been present in the structure e.g. carbonation of concrete or rusting of steel bars etc. If the depth of damage is more than ¾ inch or 0.75 inch then hydro blasting can be used for removal of damaged concrete. If structure is in conjunction with some other structure as it is the case usually then care must be taken. If depth is lesser than the above parameter then it is better to remove the concrete with hammer and chisel. Damaged concrete is not difficult to be removed hence it wouldn’t be that difficult and only that concrete will be removed that doesn’t have enough strength or damaged. Jack hammers can be used as well but it is not advisable for fire damaged structure that are already in pretty bad condition. It may even damage the structure that is in still healthy condition. Moreover it always develops micro cracking within the structure.81 Hydro demolition is a process in which concrete is removed by high water pressure. This method is used to remove both sound and damaged concrete. In repair work of fire damaged building this method is of prime importance as it can remove concrete that is locally damaged or can remove the whole overlay or concrete cover. It can easily remove concrete upto the depth it has experienced damaged even in spaces where it is difficult to reach with jackhammer or hammer 80 81 In case where reinforcement bars have been damaged and needs replacement. http://frbiz789.blog.com/2009/12/01/hydrodemolition/ accessed 15.08.2014. 46 and chisel. Serious precautions are required to use this method because water gun that has such huge pressure that it can cut through concrete can easily cut skin and bones. Hence serious precautions are required for this process. Hydro demolition is conducted by two ways. Manual hydro demolition and robotic hydro demolition. Hydro demolition is shown in the figure on the below.82 Figure 15: Hydro Blasting for concrete removal83 Advantages of hydro blasting or hydro demolition are as under  Hydro blasting is very accurate method because various variable like speed of jet, jet pressure, size of jet make possible to remove concrete upto a specific depth. These properties gives it precision required for repair jobs. As water jets removes damaged concrete easily due to crack and faults hence it can remove only damaged concrete precisely leaving sound  concrete beneath. It eliminates the vibration and micro cracking in the sound concrete of the structure and adjacent structure. This is important for repair jobs where structure has already endured heavy damage and structural stability is  already in question.  provides better bonding of bars with repair material It remove any cement or concrete left over the reinforcement bars which It prepares the concrete surface for repair job, as it scarify the aggregate and leaves a clean, rough surface of aggregate that is vital for repair material to get bonding. 82 83 http://frbiz789.blog.com/2009/12/01/hydrodemolition/ accessed 15.08.2014. https://www.youtube.com/watch?v=bZuks_1SdCI accessed 15.08.2014.   47 It doesn’t damage the reinforcement bars but infact cleans the corrosive chlorides from the surface. It is faster than mechanical measures for concrete removal.84 Disadvantages for hydroblasting are as under  It requires serious safety measures to conduct this procedure as the jet that can blast concrete can easily tear muscles or even bones. So special  suit and safety accessories are required As this method is quite sensitive and conducted by both manual and robotic means, therefore experienced and expert staff is required to do the job.85 3.4.2.2. Partial replacement of reinforcement bar/bars If fire was intense and unluckily have damaged the steel bar/s of reinforcements or if reinforcement bars were having previously lying shortcomings then they have to be accessed by experts. If it is concluded that the cross section of the bar has been seriously reduced and the steel bar can’t fulfil the intended purpose then it has to be replaced. As the whole length of steel bar is not usually replaced in repair jobs because it requires serious damage by fire to inflict any damage to the reinforcement bars. If temperature of fire was high enough that it penetrated the cover and temperature at high degrees sustained there for long enough then reinforcement bars may endure damage. This doesn’t happen very often, and even if it does then such damage is localized which demands partial removal or replacement of steel/reinforcement bars before concrete repair is applied. After damaged concrete is removed, it is important to cover healthy reinforcements with some epoxy resin which will prevent corrosion of exposed bars, facilitates bonding and remove existing salts over the surface (if any). It has to be made sure that there are no left overs of concrete over the healthy bars. 84 85 http://www.metrocorp.com.au/services-item.php?id=4 accessed 15.08.2014. http://www.metrocorp.com.au/services-item.php?id=4 accessed 15.08.2014. 48 Damaged reinforcement bars are then removed either by flame cutting or by removal of splice wire. New reinforcement bar is provided with designed splice length to ensure safe transfer of stress across the length of bar through the patch. Splicing can be provided with welding or wire wrapping and knotting. The splice must be grouted with high strength and little shrinkage grout consisting of epoxy or Portland base.86 3.4.2.3. Partial replacement of Concrete After reinforcement bars are covered with protective epoxy to protect from corrosion and damaged reinforcement bars are replaced (if any), removed damaged concrete is replaced with new one. In case reinforcement bars are repaired, then new concrete should surround reinforcement bar from all around to provide strong enough bong that can accommodate stress transfer between concrete and steel. Thumb rule is to provide 1 inch new concrete around the bars. Moreover to avoid premature corrosion of reinforcement bars, coat the new concrete surface with same epoxy that has been used to coat reinforcement bars.87 There are two basic methods to replace removed damaged concrete   Shotcrete In-situ Replacement with formwork Shotcrete is a very extensively used method in which concrete is replenished with sprayed mixture (mortar or concrete) form the nozzle with high speed which eliminates the need of compaction. The mixture that is supplied to the nozzle can be in dry or wet form. In dry form water is added at the nozzle. In fire damaged buildings, elements such as slab, can’t be easily repaired by in-situ concrete. Shotcrete provides an easy solution as it doesn’t need any compaction or formwork. A bonding agent is required to provide over the surface of old concrete 86 87 JPCL. 2011. Surface Preparation of Concrete Substrates. Page no 21. JPCL. 2011. Surface Preparation of Concrete Substrates. Page no 21. 49 to ensure good bonding between old and new concrete and to avoid cold joint. Following figure explains the phenomenon of shotcrete.88 Figure 16: Shotcrete to replace removed damaged concrete89 In-situ replacement can also be used for the replacement of damaged concrete but it cannot always be used as in case of top surface repair as in case of slabs. For vertical members like columns in situ concrete can be used but still in-situ replacement is not beneficial more than shotcrete as it requires more labour, formwork and effort. Special concrete mix is required for preventing cold joint that exists between new and old concrete. Bonding agent has to be applied to the surface as surface preparation measure same as in shotcrete. Shotcrete may require a costly mix than conventional concrete but labour and other requirements like vibration are not required which makes it more financially feasible. Moreover shotcrete can be used almost for all kind of concrete repairs (vertical, horizontal or overhead repairs). 3.4.2.4.  Advantages and disadvantages of partial removal and replacement Partial removal and replacement technique reinstate the form and shape of damaged element. It also revitalise its structural strength to reasonable 88 http://www.shotcrete.org/pages/products-services/technical-questions-archive.htm accessed 16.08.2014. 89 http://www.sustainableconcrete.org/?q=node/171 accessed 16.08.2014. 50 mean. Hence structure can continue its normal function and load pattern   of building doesn’t change significantly. Material cost of this technique is way lesser than FRP reinforcement. One striking benefit of this technique that others don’t is that it not only takes care of shortcomings due to fire damage but also covers the inherent shortcoming to somewhat. If there had been some carbonation of concrete  or corrosion of steel then it will automatically takes care of it as well. It also provides excellent fire proofing abilities as after repair structural element will be having more thicker and tight cover that is consisting of concrete and epoxy resins. Collectively they provide excellent fire resisting  properties. Concrete is a green material as it doesn’t depletes fossil fuel and waste too much energy in its manufacturing as it is in case of FRP. Hence it can  be credited as a sustainable repair technique. This repair technique offers high durability as element is revitalised by it and can serve for long time.  Due to the removal of the concrete the section of the element reduces and it can be dangerous as element may be barely stable and during  chipping damaged concrete it may lose its stability and fails. Propping is required for partial removal and replacement technique to carry or share the burden of element temporarily. If there is any heavy object that is supported by the element and it can be removed then it has to be relocated to avoid sustained load on the fresh replaced concrete  that is not in the condition to bear the burden at such early stage.  be injurious as falling material can hurt the labour and skilled workers. For overhead repair such as ceilings, removal of concrete may prove to Cold joint is always existing between old and new concrete. That would automatically be the case on replacing new concrete hence for proper bonding special surface preparing measures have to be used. Bonding 51 agent is usually required for surface treatment moreover epoxy resins are  required to add into concrete mix. Use of epoxy resins, propping, and lot of activities involved makes this measure costly and not very financially feasible when we compare it with other possible options like FRP. 3.4.3. Concrete jacketing Concrete jacketing is the retrofitting technique for structural members. In fire damaged building concrete jacketing can provide extra strength to damaged structural member. It is done by removing the existing cover of the element and providing a new concrete cover along with new reinforcement bars. It is not always necessary to remove the existing cover sometimes if cover concrete is not damaged significantly then it can be provided over the actual element. The new applied concrete jackets the existing structural element and provides much needed strength after the structure is damaged. Concrete jacketing can be done on column and beams and slab systems as well. Figure 17: Concrete jacketing process before concreting 90 Concrete jacketing has its unique demands in terms of designing. The newly added width and depth of the member changes the behaviour or structural 90 http://www.corecut-jo.com/index.php?module=services&id=6 accessed 16. 08.2014. 52 member. It automatically got stiffer and now will attracts more loads. After concrete jacketing the load pattern of the structure changes hence design has to sound enough.91 Concrete jacketing is a successful process to reinstall the strength of member but its success depends upon the monolithic behaviour of the element. The shear force must transfer from old structure and concrete jacket. For attaining monolithic behaviour surface treatment is very important. There are various methods to roughen up the surface of the concrete in the market. Any of them can be used to provide better bonding between old and new concrete. Epoxy bonding agent are applied after roughening up which guarantees the bonding of old and new concrete. This is critical to the load transfer behaviour of the structure. Steel connector are also used to facilitate monolithic behaviour and transfer of shear forces between old and new concrete.92 Concrete that is used for jacketing can be in-situ or shotcrete. Concrete jacket must be atleast 100 mm thick and of higher compressive strength of the old existing one. If it is not feasible then it should be atleast equal to the compressive strength of the old concrete. If possible then all four sided jacket should be provided to retain the symmetry, centre of gravity and neutral axis as before. Reinforcement that are provided in the concrete jacketing process should be carefully calculated and must pass all the checks of designing process.93 Advantages and disadvantages of Concrete jacketing process to retrofit the structural members is as follow.  Concrete jacketing changes the structural behaviour of the structure so structure analysis has to be done in addition. The load pattern may significantly changes hence only emphasising the need of re-evaluation. 91 Teran, Ruiz. 1992. Reinforced concrete jacketing of existing structures. Page no 5107. http://www.corecut-jo.com/index.php?module=services&id=6 accessed 16. 08.2014. 93 Teran, Ruiz. 1992. Reinforced concrete jacketing of existing structures. Page no 5107. 92  53 Change in dimension of the original member my shifts the centre of mass, gravity and neutral axis. Un-symmtericity can be generated additionally.  These factors further complex the situation.  net rentable area which is pretty loathsome factor for architects. Addition of jacketing reduces the available space and hence reduces the Due to the increment of concrete jacket, dead mass is accumulated and stiffness of the structure also increases. These factors increases the risk  of earth quake damage. Special experts are required to do the job as surface preparation is a critical activity. Shear steel connector that are provided to attain monolithic  properties require significant technical competence.  essence, this technique provides no help. The whole process takes too much time and projects where time is of Due to the number of activities and requirement of process like skilled workers, shuttering, curing of concrete etc. This technique proves to be costly in comparison to both FRP and Partial removal and replacement of concrete and reinforcement.  If structural element is repair by concrete jacketing then it enhances the flexural strength, shear capacity and axial capacity of the member. It may  strengthen the member even more than before fire damage. It also provides excellent fire proofing abilities as after repair structural element will be having more thicker and tight cover that is consisting of concrete and epoxy resins. Collectively they provide excellent fire resisting  properties. Concrete is a green material as it doesn’t depletes fossil fuel and waste too much energy in its manufacturing as it is in case of FRP. Hence it can  be credited as a sustainable repair technique. This repair technique offers high durability as element is revitalised by it and can serve for long time. 54 3.4.4. Steel Jacketing Steel jacketing is the technique in which structural element is encased by steel angles, channels and bands. This technique gives certain confinement to the element and helps to increase its flexural strength. The steel encase is filled with non-shrinkage grout. The figure bellows shows the complete process of steel jacketing. Figure 18: Steel jacketing process94 94 http://theconstructor.org/structural-engg/strengthening-of-r-c-columns/1935/ 18.08.2014. accessed 55 This method is used in structural repairs, where increasing size of element is not permitted due to any reason. It could be rules and regulations or demand by the owner to retain the net rentable floor area etc. As steel will be exposed to the weathering agents hence it is mandatory to apply protective coating against rust. In case of future fire, steel will be in direct contact with fire flames and as being excellent conductor of heat it will not be only damaged by itself but can prove to be a cause of fire spread. Figure below shows the concrete column repaired by steel jacketing. Figure 19: Steel jacketing of column95 Advantages and disadvantages of Steel jacketing re as follow  If structural element is repair by steel jacketing then it enhances the flexural strength, shear capacity and axial capacity of the member. It may  strengthen the member even more than before fire damage Steel is a green material as it doesn’t depletes fossil fuel and waste too much energy in its manufacturing as it is in case of FRP. Hence it can be  credited as a sustainable repair technique.  and can serve for long time. This repair technique offers high durability as element is revitalised by it It is pretty fast as unlike concrete jacketing it doesn’t need long curing times and number of activities are also reduced. 95 http://ramsetmbtmedan.blogspot.de/2012/09/jacketing-struktur.html accessed 18.08.2014.  56 It revitalise the structural element yet doesn’t changes its form and appearance. It also reinstate its structural strength to reasonable mean. Hence structure can continue its normal function and load pattern of building doesn’t change significantly.  As steel is prone to corrosion and rusting therefore it can’t be used without proper protection against rusting and corrosion. In marine environment, it  will have serious shortcoming. Steel could be exposed to serious temperature in future fires which may leads to the structural failure as steel wouldn’t offer long enough resistance against fire. Moreover it may spread fire to other floors as it has very good thermal conductance. Hence it is mandatory to provide fire proofing over  the steel jacket.  FRP especially because of handling costs. Cost of this retrofitting technique could be higher than other measures like Experts and skilled labour is required to fulfil the job. 3.5. Other Methods of retrofitting and rehabilitation For retrofitting of structure and providing more strength to the structure few other methods are also practiced. It is not possible to discuss all in this text. So for the sake of mentioning few common solutions to fire damaged structures are as under. If damage due to fire is not extensive and not concentrated on some defined locations but infact equally damaged the structure. Resultantly strength has been reduced but still structure seems to be sound enough. Above mentioned techniques makes it too costly and unfeasible to retrofit. In such scenario overall demand of the structure can be decreased. This measures may be not always possible as it is not possible to shift some equipment installed or the purpose of the facility can’t be altered. Still this is possible in some cases to go with this 57 solution. Another possibility in case of this technique is to replace the heavy equipment or members of the structure or building with lighter ones. This will reduce the weight of the building which ultimately makes it suitable again for purpose. Additional structural members can also be provided in case of rehabilitation of fire damaged building. This may be done if structural element has undergone very serious damage and it can’t be revitalised to its past strength. In that case new structural members are provided. This method will actually change the structural behaviour of the structure. Load path will definitely changes. This is a desperate measure and only done if it is a must to retrofit and rehabilitate the damaged building as it has significant importance. This technique is often done by prefabricated element. For example providing a steel beam beneath a severely damaged beam as a support to actual beam. Provision of some extra column as it can be seen that beam has been damaged and undergone severe deflections. Hence new columns will shorten the span and ask for less load sharing from each part. Cracks are often case of fire damage in R.C.C buildings. Fire can also create radial cracks around the reinforcement bars. These kinds of cracks cause debonding of steel and concrete. Such scenario will cause loss of load transfer between two materials. Structural cracks can cause dowel action and prove to be a mile stone of ultimate failure. To take care of these cracks epoxy injections are used. The epoxy injections can also alone take care of the problem but if problem is extensive then these measure can complement other measure like FRP reinforcing or partial removal and replacement of concrete and reinforcement. Etc. The efficiency of the measure is dependent on the skill of the workers and staff. This comprehensively conceals the cracks and nip the evil in the bud. 58 Summary Rehabilitation and retrofitting starts with cleaning of the property. After fire, building has to be cleaned as soon as it is cleared to be entered. It will stop further damage due to the water sprinkled to extinguish fire and due to the deposition of smoke & soot. It is necessary to remove smoke and soot from the surface of belongings and building likewise. Otherwise it will damage them because of acidic fumes it may contain. Moreover, smoke smell will be difficult to remove. To remove smoke smell thermal foggers and ozone machines can be used but comes with their respective shortcomings. Air scrubber provides better solution than former two. Smoke and soot that are deposited on the surface of building and can’t be removed by ordinary methods can be removed by soda blasting. It is a green practice to remove smoke and soot deposits with soda blasting rather than harsh chemicals. Combustible non- structural members and utilities are often in poor condition after fire. If they can be repaired economically then it is better to repair them otherwise replace them. Non-combustible non-structural members are not often damaged much. Usually only cleaning with soda blasting is required. FRP reinforcing sheets and plates are commonly used for various kind of rehabilitation techniques including fire damaged repairs. FRP has many inherent characteristics that make it very good repair material like excellent tensile strength, durability, light weight, nonmagnetic behaviour and ease of handling but also has serious shortfalls specially sustainability and future fire resistance. It also allows excessive deflections in structural members that is not very desirable. It is weak in shear resistance and suspected to damage if not handled properly. Partial removal and replacement of damaged concrete and steel is another method of concrete structure retrofitting. It may not be wrong to say that it is the most popular method of retrofitting. It can be used in combination with FRP reinforcing. In this technique concrete is removed carefully that have been damaged with the help of hydroblasting or else. Hydroblasting is good method 59 for this purpose as it also prepares the surface and rinse out any rust that may be present over the reinforcement bars. Then surface is prepared and concrete is provided again either by shotcrete or in-situ casting. This method is old and tested method. It doesn’t change the dimensions of the structural element and also take care of any inherent shortcomings that may present in the element. It provides good fire protection and a sustainable retrofitting technique. It requires propping sometimes to support the member until it is fully repaired. Concrete and steel jacketing are mainly repair or strengthening techniques for seismic design or repairs. But can be deployed for fire retrofitting. Concrete jacketing is done by jacketing a member with extra layer of concrete preferably all around after removal of cover that has been damaged. Reinforcements are also provided in concrete jacket. Success of the method depends upon the monolithic behaviour of jacket and original structure and design competency. It provides better fire resistance and also a green practice. Steel jacketing, is the same philosophy but here we jacket with steel instead of concrete. It doesn’t alter the dimensions of the member but at the same time it is suspected to fire and rusting hence protective coating is a must. Along with these retrofitting methodologies some other techniques can also be practiced like reducing the load over structure by change of usage, construction of some new structural members, provision of extra prefabricated member beneath an already existing one and epoxy injections etc. All these methods are not common ones but can be used alone or in combination with other measures. 60 4. Feasibility study Evaluation of the fire damaged building, put us in the position where it is possible to understand the condition of the building. Decision regarding building has to be made, that either, it should be reconstructed after demolition or rehabilitated and retrofitted. To make such decisions comprehensive, elaborated and structured feasibility study is required. The decision making process is quite complex. Every case has its own uniqueness and demands that differs from case to case. Fire damage is not consistent. Sometimes fire stays long but doesn’t damage much while contrary to this sometimes fires of medium tenure inflicts serious damage. Design of the facility has a serious role to play in it. If design is comprehensive and fire has not been able to stay for long time, then it inflicts small damage which can be repaired. Unfortunately if structure has endured serious damage then decision making is not such an easy job. Evaluation of the building and testing must be practiced over it, to determine its residual strength. If building can be restored to code acceptance level, after fire, then it is possible to restore it, but many time code requirements and local laws makes it difficult.96 Many factors are involved in the decision making process. Economy and code requirements are not the only factors that are considered. Life span of the proposed solution is also important from sustainability and life cycle analysis perspective. Repairs are greener than demolition and reconstruction97. In case of commercial buildings, time for which building will be under construction or repair also cause loss of business. If decision is controlled by some supreme factor like building is of historical importance e.g. Reichstag or building facilitates business or activates that can’t be compromised like national security e.g. Pentagon. Then economic factor doesn’t count. But if there is no such supreme limitation as it is in normal cases then independent feasibility study is required to attest the economic and technical viability of the proposed solution. It can be rehabilitation 96 Michael Hayes. 2012. Rebuilding After a Fire. Page no 1-5. 97http://www2.buildinggreen.com/article/retrofits-usually-greener-new-construction-study-says accessed 10.08.2014. 61 and retrofitting or demolition and reconstruction. Same feasibility study are sometimes also required to compare two proposed solutions of same class. For example should the structure be retrofitted by FRP reinforcing or partial removal and replacement technique? Which one is technically and financially more superior? Here in this chapter we will discuss financial and technical aspects of feasibility study. 4.1. Technical Aspect There are various prospects of technical feasibility. Technical feasibility of building’s retrofitting and rehabilitation dictates that is it feasible to repair and reestablish the building and can structure be repaired to the point after damage that it can serve its intended purpose or it should be demolished and reconstructed. There are many aspects to look after in technical feasibility study of repair and retrofitting of structure. Each case of building rehab is a unique case, so to cover all the aspects is not possible. These aspects vary from case to case and from element to element. 4.1.1. Technical aspects of structural members In technical feasibility of structural elements, we at first number every structural member according to a nomenclature. For example, columns can be represented by CL and then be followed by a number which can indicate the floor and then it is followed by column number. So for 3rd column at ground floor it would be CL 0,3. Hence a representation system will dictate that which columns are damaged (which is important for partially damaged building). After proper representation of damaged elements, technical feasibility of structural members is carried out with the help of results obtained from condition assessment and desk study. Each kind of element has its own behaviour and it is better to deal with each type of element separately. 62 4.1.1.1. Columns Columns are the vertical load bearing members and lowest in the super structure of the building. Columns usually bear heavy damage in case of fire as they would be fully exposed to the fire. Under fire and sustained load it is extremely important for columns to carry on their purpose otherwise structure will collapse. Columns usually outperform their duties and don’t collapse until the reinforcement fails and damage is usually limited to the damage upto the cover. Various tests as described in condition assessment of fire damaged buildings can be performed to identify the extent of damage. Windsor probe test results can’t be discussed as they vary from concrete to concrete. Concrete mix and aggregate type are two important factors in the results values. Similarly it is unlikely, to standardise the results of core sampling and testing on the basis of which damage classification can be performed. This is mainly because of their length to diameter ratio varies which usually fluctuates between 1 to 2 for compressive testing. As core testing and tensile testing directly gives us the values of the compressive strength of concrete and tensile strength of steel hence they can be directly compared with the design strength of respective materials in the structure or compared with the results obtained from undamaged respective material. Figure 20: Fire Damaged Concrete Column98 98 http://www.barberhoffman.com/portfolio/project-detail.aspx?PortfolioID=113 30.07.2014. accessed 63 Table 6: Technical feasibility study of column retrofitting RHT99 UPV100 Petrography Cover Main (Rebo (Pulse Results Damag Reinfor- Dam und Velocity Temp101 (C) e Depth cement age Value) km/sec) (mm) condition102 Structurally sound/undamaged, Some surface damage due to smoke, water, bio waste etc. > 40 > 4.6 < 70 None Unaltered Little damage to plaster finish , Concrete remain undamaged > 40 70 to 300 None Unaltered Substantial loss of plaster finish, Concrete turns pink, minor spalling, serious micro cracking, Reinforcement is undamaged if cover is <26 mm 40 to 30 300 to 600 < 26 <25% exposed, none buckled Plaster is totally destroyed, Concrete is buff coloured (whitish grey), Concrete cover is locally removed revealing reinforcement bars, Reinforcement bars are locally damaged but still re-useable 30 to 20 600 to 900 < 42 <50% exposed, not more than one bar buckled Seriously damaged, More or less total removal of concrete cover, concrete confined within reinforcement may be damaged too, Reinforcement bars bear serious damage, may be buckled. Distorted. < 20 > 900 Total loss of cover >50% exposed, more than one bar buckled Degr Item Description ee of # damage 1 CL (n,n) 2 CL (n,n) 3 CL (n,n) 4 CL (n,n) 5 CL (n,n) 99 of 3.7 to 4.6 3.0 to 3.7 2.1 to 3.0 < 2.1 Rebound Hammer Test. Ultrasonic Pulse velocity. 101 Temperature at the surface of concrete in Celsius. 102 http://www.gbg.co.uk/?page=strfirevissurv accessed 29.07.2014. 100 64 4.1.1.2. Beams Beams are the horizontal members of the structure that bears shear and flexural load to provide the clear space underneath. In the event of fire, beam has to remain structurally sound and perform its functions. Beams are usually significantly deflected, in case of serious fires under the sustained and fire loads. Damaged beams can be repaired and it turns out to be first preference after damage but they can be replaced as well. Replacement of concrete beam is usually done by steel beam but sometimes concrete beams are also placed just under the existing beam. Various tests are performed over beams as described in 4.1.1.1 “Column” Degr ee of Item # Description of damage 103 Dam age 1 BM BM (n,n) 3 BM (n,n) 103 UPV105 Petrogr Cover Main (Rebo (Pulse aphy Dama Reinfor- und Velocity Results ge cement km/sec) 106 Temp Depth condition107 (C) (mm) < 70 None Unaltered 70 to 300 None Unaltered 300 to 600 < 26 <25% exposed, none buckled Value) (n,n) 2 RHT104 Structural soundness is intact, Some surface damage due to smoke, water, bio waste etc. > 40 Surface crazing and minor spalling , Concrete remain undamaged, Smoke deposited > 40 Significant spalling along adjacent planes exposing main reinforcement of outer surface of corner bars, Concrete turns pink, serious micro cracking, Reinforcement is 40 to 30 > 4.6 3.7 to 4.6 3.0 to 3.7 SD0107. Repair of Fire Damaged Structures. Ppt. slide no 14. Rebound Hammer Test. 105 Ultrasonic Pulse velocity. 106 Temperature at the surface of concrete in Celsius. 107 http://www.gbg.co.uk/?page=strfirevissurv accessed 29.07.2014. 104 65 undamaged if cover is <26 mm 4 BM (n,n) 5 BM (n,n) Concrete is buff coloured (whitish grey), Serious spalling reveals reinforcement bars, Deflections are minor, wide structural cracks appeared. 30 to 20 Seriously damaged, Heavily deflected and fractured, More or less total removal of concrete cover, Main Reinforcement bars buckled. < 20 600 to 900 < 42 <50% exposed, not more than one bar buckled > 900 Total loss of cover >50% exposed, more than one bar buckled 2.1 to 3.0 < 2.1 Table 7: Technical feasibility study of Beam Retrofitting 4.1.1.3. Floor/Slab Panels Slab panels provide the solid surface at an elevated ground. It is shallow in depth while relative in length and width. It is a horizontal structural element which is usually designed for flexural and shear loads. Sometimes point loads are also considered. Same as column and beam, various tests are performed over it as explained in 4.1.2. These floor or slab panels are mostly prefabricated and hollow with pre-stressing. Due to these characteristics it is not as resilient to fire as columns or beams usually are. Moreover the temperature in fire is maximum at the top of the flames. Hence these members are directly in max temperature zone. These panels can be effectively repaired and retrofitted unless pre stressed steel has endured serious damage and the slab panel is completely un-functional. Technical assessment of damage of slab element is as follow. Figure 21: Fire Damaged Slab108 108 http://caltransd7info.blogspot.de/2011_12_01_archive.html accessed 31.07.2014 66 Degr Item Description of RHT110 UPV111 Petrogra Cover Main ee of # damage109 (Rebou (Pulse phy Damag Reinfor- nd Velocity Results e cement km/sec) Temp112 Depth condition (C) (mm) 113 < 70 None Unaltered 70 to 300 None Unaltered 300 to 600 < 26 <10% exposed, none buckled, all adhering 600 to 900 < 42 <20% exposed, generally adhering Dam age Value) 1 SL (n,n) Haven’t endured any structural damage, Some surface damage due to smoke, water, bio waste etc. > 40 2 SL (n,n) Smoke deposited, Suspended ceiling is seriously damaged, few surface spalls on concrete with few surface cracks > 40 Spalling is more intense especially on concrete ribs (if any) or under the pre-stressed steel exposing some reinforcement locally. Concrete turns pink, serious micro cracking, Reinforcement is undamaged if cover is >26 mm 40 to 30 Concrete ribs are substantially spalled and reinforcements are majorly exposed but still adhering, Concrete is buff coloured (whitish grey), Deflections are minor, Structural cracks apparent. 30 to 20 3 4 5 109 SL (n,n) SL (n,n) SL (n,n) > 4.6 3.7 to 4.6 3.0 to 3.7 2.1 to 3.0 Main Reinforcement bars < 20 > 900 Total separated, damage is loss of serious, Heavily deflected cover < 2.1 and fractured, More or less total removal of concrete cover. Table 8: Technical feasibility study of Slab Retrofitting SD0107. Repair of Fire Damaged Structures. Ppt. slide no 14. Rebound Hammer Test. 111 Ultrasonic Pulse velocity. 112 Temperature at the surface of concrete in Celsius. 113 http://www.gbg.co.uk/?page=strfirevissurv accessed 29.07.2014. 110 >20% exposed, mostly bars are separated 67 4.1.2. Technical aspects of non-structural members Non-structural members like partition walls, plumbing, HVAC, thermal insulations, openings (windows, doors etc.) they can be easily assessed by visual inspection and damage class can be confirmed. It is unusual to conduct test and detailed diagnostic measures over it. The degree of damage for non-structural members and utilities are assessed by visual inspection as described in 2.3.1 (Table 2). System of representation of various kind of elements and utilities are represented can be represented by same nomenclature as described in 2.1. For example door no 5 on 2nd floor can be represented as DR 2,5. 4.2. Financial Aspect Enterprises and companies has only 3 goals in corporate world “Money, Money and Money”. This phrase may be an exaggeration of reality but reflects the importance of financial factor in any business decision making process. When real estate business is under the lime light, importance of financial factor only magnifies. Therefore, decision making regarding fire damaged building, either it should be demolished and reconstructed or rehabilitated and retrofitted, very much depends upon the financial factor. Though it is not the only important factor but one of the most important factors. Feasibility studies is done to outline the financial circumstances attached to the respective proposals. Many financial feasibility analysis tools are available and have been practiced for the general financial calculations e.g. net present value, Payback period etc. They are more or less universal tools that are used for all kind of financial feasibility studies either it is for a new development or sustainable repair etc. They are quite useful as well. In financial analysis one thing is quite common. There are lot of assumptions involved and time required to estimate these assumptions should be proportional. There are obviously factor that are more sensitive than others therefore more time should be logically spent on their extraction than others. Moreover the knowledge is quite short in the beginning but it increase as the project gets closer to reality. Therefore it is required to 68 update the financial feasibility analysis as more accurate and precise data is obtained.114 4.2.1. Preliminary requirements There are certain factors that must be considered before financial analysis is conducted. They are given below115   Analyse the nature and scope of proposal.  by bank or investor.  cash flow or accounting). Evaluation of funds available and capacity of generating investment either Decision over format of data that has to be collected (either it should be Limitation of the financial tools that are used for analysis must be identified. Otherwise results will be misleading and would be like cutting an apple  with a hammer or trying to open a walnut with a knife. Confidence in obtaining meaningful precise data about the proposal. 4.2.2. Structure Structure of financial feasibility consists of following sequential parts116 i. Realization of all associated costs ii. Realization of all associated incomes iii. Analysis calculations by analysis tools iv. Risk Analysis v. Decisions based upon analysis. Structure of financial analysis describes the format of work. It must be decided in the beginning of analysis. 114 Matson. 2000. U.S. Department of Agriculture; Rural Business-Cooperative Service, Service. Report 58: Vital Steps, A Cooperative Feasibility Study Guide. Page no 1-4. 115 Helfert. 2001. Financial analysis tools and techniques: a guide for managers 1st edition. 116 Zizzo. 2014. Life cycle costing: Financial costing. Page no 6. 69 4.2.3. Realization of all associated costs In this step, all costs that may play their part in the appraisal of proposal must be included. There will be many different kinds of cost associated to the financial calculations. It depends upon the approach selected for the cost calculation and the time span for calculations. In general costs are divided into four basic categories for financial analysis namely; construction costs, maintenance costs, operational costs and end of life costs. This is the costing model that is used in Life cycle costing approach. Now it depends upon the scope of the financial analysis and the analysis tool that is used for the calculation of costs. Life cycle approach is not compatible with all analysis tools and independently it can’t decide for the better proposal. It is better integrated with the NPV analysis method. LCC can be regarded as NPV of costs as NPV takes cash flow in present value similarly LCC takes only all costs in present value.117 For fire damaged buildings’ financial analysis, it is not very feasible to calculate costs by LCC technique because there are certain conditions to be fulfilled for using this technique for comparison purpose. Most important of them is function equivalence. LCC costing for repair may or may not have function equivalence of reconstructed building. So if this condition is unfulfilled then LCC methodology can’t be used. For financial analysis of fire damage buildings detail investigation must be conducted to calculate all the cost that are incurring over the reference life span of the building with relative accuracy. Special focus must be planted over financing, maintenance and operational costs. 4.2.4. Realization of incomes Incomes that are going to be obtained from the proposed investment over the duration of reference life should be identified and analysed. It would be good practice to check assumption with market analysis. Assumptions made in income calculation must be comprehensively described and justified. Special care is 117 Zizzo. 2014. Life cycle calculation methodology. Page no 4-53. 70 required to deal with the assumed data. As it will decide for the course of projected profit or loss. 4.2.5. Analysis calculations by analysis tools There are different analysis tools present for use. They can help in calculating financial feasibility of different proposals. There are lot of analysis tools that differentiate from one another on the basis of their methodology short comings and working principal. Financial feasibility can be calculated on the basis of accounting profits/losses (from actual business financial statements) or by projected cash flows. Projected cash flows is the better option as it accounts time value of money and can be used for both new businesses which has no financial statements yet. Moreover it has a standardised method for calculating values whereas accounting profits can be calculated in several different ways e.g. inventory listing, depreciation methods etc. Few methods of financial analysis will be presented in this study.118 4.2.5.1. Payback period Payback period is pretty basic method for financial feasibility analysis. It determines that when the costs and incomes will break even i.e. how much time it will take for the investments to pay back themselves. This method has very obvious shortcomings. It doesn’t account for time value of money. Though it can be taken care by discounted pay back method but still it doesn’t fulfil the requirements for a good financial analysis. The reason is that it only informs us that till when investments will be returned in units of time but doesn’t give any information about the profits. Because break even period is not the economic life of the building. Building will continue to serve afterwards. Hence two different proposals can’t be compared with this method truly. 118 Björnsdóttir. 2010. Financial feasibility assessments: Building and Using Assessment Models for Financial Feasibility Analysis of Investment Projects. Page no 1-18. 71 4.2.5.2. Financial ratios There are different financial ratios that can help in analysing the financial feasibility of investment. They can’t be used independently for calculating financial feasibility but can be really supportive in giving perspective analysis about investments. Financial ratios can be used for the analysis on accounting value bases. From financial statements, values are used to calculate these ratio. Projected value can also be used to better understand the impact of decisions. There are different kinds of financial ratios that are used as given below   Liquidity ratios  Profitability ratios  Asset management ratios  Market trend ratios Debt management ratios.119 4.2.5.3. Net Present value Net present value is the difference of present values of all project costs and incomes. Costs of the project that are intended to be included happens at different time. Similarly income or return from the investment also happen at different time. NPV discounts the future cash flows to present value to include time value of money which gives rational meanings to the analysis. In the end, sum is obtained for the inputs and outputs to calculate NPV of investment. Critical factor in determining NPV is discount rate. It is explained by Park (2002) as “MARR” minimum attractive rate of return. It is the rate which is achievable by the investor if he invests his money to an alternative investment i.e. rate of interest from bank or other alternate investment120. Moreover, planning horizon or reference life of the project is estimated. This has a telling effect over the calculation results. So must be estimated with care. At the end of reference life, we get NPV of the 119 120 Park. 2002. Contemporary Engineering Economics. 3rd edition. Page no 288- 291. Park. 2002. Contemporary Engineering Economics. 3rd edition. Page no 288- 291. 72 investment.121 Decisions are made upon its basis as shown along with the formula used for the calculation of NPV.    NPV(i) = 0, Investment breaks even NPV(i) < 0, Reject the investment NPV(i) > 0, Accept the investment Here i= MARR. For comparing two investment proposals, the proposal with higher NPV should be selected. But for the purpose, Zizzo (2014) said that same interest rate or “i” and reference period/life should be selected for which sometimes small changes have to be made. Formula for calculating NPV as described by Park (2002) is given below122. (Park, 2002) This method is not really feasible for comparisons of two different proposals that are not of equal life time (n) as it is a common case when dealing with fire damaged buildings. 4.2.5.4. Internal rate of return Internal rate of return is the interest rate at which Net present value is equal to zero. This interest rate set a criteria for the investors to make decision that either they should accept it or reject it, consistent with net present value analysis. For 121 122 Zizzo. 2014. Life cycle costing: Financial costing. Page no 24-28. Park. 2002. Contemporary Engineering Economics. 3rd edition. Page no 289. 73 simple financial calculations where we have only 1 change in sign with respect to cash flow. In those cases i* is same as IRR. In complex cases, story may be different. IRR is equal to i* (rate of return) when following mathematical expression gives zero value. The following formula is given by Park (2002).123 (Park. 2002) Investor are usually more interested in getting profit rather than breaking even. Their target is established by MARR. So MARR and IRR can be used to make decision about investment based on following criteria    IRR = MARR; Break even so decision is indifferent IRR < MARR; Reject IRR > MARR; Accept There are certain draw backs attached to the IRR method. First and foremost it is not consistent. It may give more than one IRR if there is a complex scenario i.e. if there is more than one sign change in the cash flow. NPV is generally considered as better method than IRR but the importance of IRR can’t be ignored as in some cases it may prove to be better than NPV.124 4.2.6. Risk analysis As the input data collected for the purpose of financial analysis is based upon projections and many assumptions are involved in it as well. Therefore there is always a risk of uncertainty, wrong estimation or change in assumed values though they are taken with great care and responsibility. To deal with this issue risk analysis is done by following techniques 123 124 Park. 2002. Contemporary Engineering Economics. 3rd edition. Page no 410. Lee. 2009. Financial Analysis, Planning And Forecasting: Theory and Application, 2nd edition. 74 4.2.6.1. Sensitivity analysis Sensitivity analysis gives the investor an insight about the risks that are associated with the change in input values. It is conducted by changing the input value one at a time to understand its effect on the output. In this way the most sensitive input variable is identified. The most sensitive input variable is then estimated with even more accuracy to mitigate the risks and to get better analysis. It also tells the investor that which parameter can have a significant effect on the project. Best practice for sensitivity analysis is to plot graph of different sensitivity analysis for different parameters.125 4.2.6.2. Scenario analysis Scenario analysis is used to define the best and worst case scenarios compared to the base case. Base case is the analysis made by analysis methods explained above. Then it includes the change in the values of key variables and the range over which they can possibly fluctuate. Extreme cases are identified in case of each variable or parameter. Worst scenario of each parameter is accumulated and same goes for best scenario of each parameter to determine worst and best case scenario. One drawback of this system is that it only gives information about extreme case and doesn’t inform about the case that will lie in between them. 126 Summary Feasibility study is required to estimate the viability of the proposal presented as a solution for fire damaged buildings. Any feasibility analysis for fire damaged buildings must include both technical and financial aspects. 125 126 Zizzo. 2014. Life cycle costing: Financial costing. Page no 34-52. Zizzo. 2014. Life cycle costing: Financial costing. Page no 34-52. 75 Technical feasibility plays half role to decide that either fire damaged concrete building should be rehabilitated or demolished and reconstructed. For the task, first the results obtained from condition assessment are assembled and analysed to assign the degree of damage, building has endured. To assemble, analyse and getting meaning full information from the data obtained evaluation tables in 4.1.1 are developed. This meaning full information will be then analysed to develop the technical aspect of feasibility study. Financial feasibility makes the second half of the feasibility analysis that makes the basis of decision making. Financial feasibility calculation for demolition and reconstruction or retrofitting and rehabilitation are similar to the financial feasibility calculations of new development. Before conducting financial feasibility analysis, preliminary assessments regarding the limitations of respective proposal and understanding of its scope will definitely help a lot. It will set the tone of the financial analysis. Financial feasibility starts with the calculation of costs. LCC technique can’t be used for comparison as it doesn’t fulfil the functional equivalence criteria of compared proposals. Various analysis methods are available to choose for financial analysis like payback period, NPV, IRR etc. Only the mentioned methods have been discussed along with their respective pros and cons. After analysis, the risk analysis has to be conducted to determine the most sensitive parameters in the cash flow. So that they can be more accurately calculated and right amount of effort is provided to all variables according to their significance. Best and worst case scenarios are also identified to understand the positions in which investor can possibly be. On the collective basis of technical and financial analysis decision must be made. 76 5. Results, findings and problem Definition Results of studies that have been done until now presents following results, findings and problems. 5.1. Results Concrete buildings are damaged under the event of fire. The damage is not only caused by fire. Smoke, soot and water (fire extinguisher) contribute in overall damage. Degree of damage depends upon many factors like temperature and duration of fire, design of building etc. Nobody, should enter the building unless structure is secured (if not) and building got clearance from respective authorities. Water should be dried out at first which would otherwise cause further damage and accelerates deterioration. Concrete buildings are naturally much tolerant to fire, thanks to the fire proofing properties of concrete. In concrete buildings, mostly fire damage is retained by concrete cover and steel is escaped from damage. Desk study has to be done before evaluation of building, to understand salient features of building and fire. Condition survey is conducted on the building (for both structural and no structural members) to have basic understanding about degree of damage. It is done by means of visual inspection, hammer tapping and chiselling. Condition Assessment is conducted on structural members to precisely access their condition and to determine actual degree of damage endured. Mostly NDTs are practiced to find out the residual strength and stability of structure. Nondestructive test like Schmidt hammer, UPV test and penetration resistance test gives good idea about the structure’s residual strength, if they are conducted properly. They can’t be totally relied upon owing to their inherent shortcomings as none of them directly calculates the strength of concrete or steel. Instead, all NDTs uses indirect correlations to evaluate the certain criteria which is not necessarily be strength. To sum it up, NDTs results have 65% to 85% accuracy. They can serve up the purpose for some case (especially those buildings which are not much damaged) but can’t be considered as authority. Cases, where better 77 accuracy is required, core sampling & testing and petrography test should be conducted for evaluation of concrete. For steel, tensile test and SEM microscopy can provide accurate evaluation. Combination of core sampling & testing, petrography and tensile test is enough to thoroughly understand the condition of conventional R.C.C buildings. If pre-stressing is involved then SEM microscopy may be added. These tests are bit costly in market hence they should be used as per requirement if necessary. Condition survey and condition assessment evaluates the condition of building. After evaluation it is required to decide about the fate of building. Generally, rehab is more sustainable and economical option but this can’t be true for all cases. Moreover, no certain work or proof is there to establish the statement as a fact. To determine that whether building should be demolished and reconstructed or rehabilitated and retrofitted, comprehensive feasibility study (technical & financial) should be conducted. For technical aspect of feasibility study, data obtained from condition survey and condition assessment is of vital importance. That data is random and scattered so it must be properly structured and then analysed to help in carrying out technical feasibility studies. Financial aspect is very vital as well. In most of the business cases, it is the most important factor. Various financial analysis methods are used to understand the viability of investments. Risk analysis must be done in order to take sound investment decisions. Retrofitting and rehabilitation starts with cleaning activity, after it is established as a better option by feasibility study. Smoke and soot should be cleaned from the surface of building and belongings which would otherwise deteriorates them and smoke odour will be a permanent stay. Thermal foggers, ozone machines and air scrubbers are used to take care of smoke odour. Air scrubber is the safest option among them. Combustible non-structural members /parts of the building are often in poor condition beyond repair so would be replaced. Generally, non-structural members and utilities that are not much damaged needs surface treatments only. Soda blasting is good, sustainable, economical and effective technique for surface treatment. Patching and varnishing can also be done if required. HVAC, electrical wirings and other utilities can be repaired if damages are limited 78 otherwise have to be replaced partially or completely. Structural members can be retrofitted by FRP reinforcing, partial removal and replacement of damaged concrete and steel, concrete or steel jacketing and epoxy injections. FRP reinforcing technique is a good measure with many excellent advantages like performance, light weight etc. but falls short on the criteria of future fire proofing and sustainability. Partial removal and replacement is a sound technique for retrofitting and most popular one. It is a sustainable method with good fire proofing qualities but it might prove to be bit more costly than FRP reinforcing. Partial removal can put extra stress on adjoining members hence needs propping. Concrete jacketing is used basically for earthquake retrofitting but can be used for fire damaged concrete buildings in certain cases. It is fire proof and sustainable technique but may alter the structural behaviour of structure. It changes the dimension of members. Steel jacketing is more suitable than concrete jacketing for the fire retrofitting and it also doesn’t change the dimensions of members significantly. It is sustainable but needs protection from fire and rusting with a protective coating. Epoxy injections are used to fill cracks and to make up for the loss of bonding between steel and concrete. 5.2. Findings and problem definition Literature study was quite helpful in context of building evaluation after fire damage. It helped understanding the condition assessment and condition survey. Comprehensive articles, journals, books and internet sources are available over the context of condition assessment and condition survey. It comprehensively covers evaluation techniques presented in the thesis. Retrofitting and rehabilitation measures are again comprehensively covered in literature. There have been more than sufficient knowledge available for the selected techniques of structural and no-structural rehabilitation and retrofitting of fire damaged concrete buildings. FRP, partial removal and replacement and other techniques have been observed in various case studies. Partial removal and replacement technique has been bit more favoured but it is justified by its characteristics like sustainability, fire proofing, excellent performance, retaining 79 the strength and physique of structure. So industry practice seems rational and result oriented. The biggest concern is over decision making process. Literature study doesn’t provide with any suitable structure for feasibility study that is specialised for decision making in case of fire rehabilitation. Financial feasibility studies has been available in abundance but they are general purpose financial studies. Same financial feasibility analysis method are used for nearly all investment cases but as fire damage buildings are not ordinary case. Here we need comparison between proposed solutions with certain conditions. Limitations of conventional analysis methods like NPV, IRR, payback period is not always suitable especially in complex cases because of these limits. Whereas literature for structured technical feasibility have not been found. Probable reason for that is, there are lot of factors and variables involved in any such studies as every case is a unique case. Hence serious efforts are required to establish a structure and technique for such feasibility study which can help in taking confident decisions. Whether building should be rehabilitated and retrofitted or demolished and reconstructed? How to determine overall feasibility involving both technical and financial feasibilities? Can comparison between two rehab techniques be made? All these questions are important questions while making decisions and need to be properly answered. Literature study provides fair knowledge over the process of dealing with fire damaged concrete buildings but it has some issues. It lacks some knowledge that is required for complete understanding of the decision making process. Solutions to fix the problem: To develop a feasibility analysis tool that can give guidance in decision making process (described in section 4.). It should include both financial and technical feasibility. So that the final recommendation it will give, must have weighted contribution of all significant factors involved. 80 6. Solution development Technical and financial feasibility tools would be separately developed and then merged to give birth to overall feasibility analysis tool. This technique is adopted to attain accuracy, which would be hammered otherwise, with the involvement of too many variable at once. The tool that is developed here is a basically a parametric mathematical model. At first, it account for technical analysis only. Later, it got contribution from financial analysis and becomes overall feasibility analysis tool. It is developed at first on its unique philosophy of accounting various parameter that are most significant for feasibility study according to their importance in respective case. Afterwards, they have been tested and here starts the loop of testing and improvement, until it got its current shape. 6.1. Technical feasibility analysis tool Damage of structural and non-structural members are identified from the analysis of data assembled in tables presented in 4.1.1 and 4.1.2. After damage is identified, it’s time to conduct technical feasibility study. Technical feasibility analysis is governed to decide that whether it is recommendable to rehab the building instead of demolishing and reconstructing on technical ground. Structure’s condition and its chances of getting its old strength back completely or upto the extent where it can perform its intended function are studied. Upon these facts and figures, it is decided on technical ground that whether it is worthwhile to rehab the building or to demolition and reconstruction, is the better answer to the problem. Factors that are important and considered in the technical feasibility analysis are described below 6.1.1. Degree of Complexity “C” As described earlier that every case is a unique case and holds its own demands and requirements. It has its own structure, degree of damage etc. Similarly complexity is very much oriented upon the nature of element and the structural system. For example. Normally, it is easier to replace damaged column with a 81 new one than it is to replace beam. Reason behind this is that, in frame structure, beams are sandwiched between slab (on upper side) and columns (on lower side). So if beam is to be replaced then it will have an obvious effect on more adjoining members. While in case of columns it is only in contact with beam or slab directly and disturb less adjoining members. So effect on adjoining member, plays its part and considered as one of the most important factor in order to decide degree of complexity. Method of repair or replacement is another important factor. The technique that is used to replace or repair the element is vital. For example to repair a beam, it might not require the vertical temporary support from beneath by formwork (propping) but for beam replacement propping or may be hydraulic jack support or any other kind of strong support is required that can replace the function of beam for time being. If another beam is provided beneath the already existing beam then formwork requirements will provide the complexity. For replacement of concrete beam with steel one may require special measures to lift it. Hence method of repair or replacement add to the complexity level. Design requirements also adds up in the complexity level. As described every case is a unique case, so degree of complexity differs from case to case. It also differs for repair and replacement in same case as well. Degree of complexity is assigned in a numeral figure from 1 to 5. One being the lowest and 5 being the highest degree of complexity. The assignment of degree is based upon the opinion of technical staff, engineer and analyst. Moreover case specific analytical approach can be used for assigning the degree of complexity. For example, for replacement job of roof and non-structural members it can be assigned as 1, for load bearing walls it can fluctuates between 1 to 2, for columns 2 to 3 and for beams and slabs from 3 to 5127. 6.1.2. Life expectancy of solution “L” Life expectancy is number of year the proposed solution (repair or reconstruction) will last. Its unit is “year”. The repair will revitalize the structure or other utility and how will it impact the overall life of the building. Both, overall remaining expected life of the building and expected life of the solution are 127 These figures are highly subjective and based upon the opinion of the author. These figures are for normal cases excluding the effect of any special condition/situation that might be present. 82 considered. For technical feasibility analysis, the lesser figure in expected life of the building and the expected life of the solution is taken as life expectancy “L”. The reason behind that is to make sure that proposed solution will serve for its expected life “L”. For example if the remaining expected life of building is 30 years and expected life of reconstructed new beam is 50 years then we will consider 30 years in analysis because it will only be able to serve us for next 30 years after which building will complete its expected life and will be demolished. In which case, the new beam wouldn’t be able to serve upto its expected life (50 years). 6.1.3. Time required for proposed solution “T” Time is another important factor. T is the number of days required for the proposed solution (repair or reconstruction) to be executed. Time is money. In case of loans and investments made by investors it is more pressing issue. Moreover the building services and the purpose of the building sometimes make it more critical and important e.g. state department building, parliament house of state or house of commerce etc. Time unit can be months if the proposal duration is too long and undermines the other factors involved. This may happen in huge projects where multi complex buildings have to be rehabilitated. Normally in cases of elements repair or reconstruction, number of days are considered as units. Anyways, for each case analyst can select suitable time unit as per his own approach but same unit should be used for both repair and reconstruction comparison analysis. 6.1.4. Degree of damage “D” Enough debate had already been done on this factor especially in 4.1.1 and 4.1.2. Degree of damage is the extent of damage that the element of the building has endured. It is decided by the proper technique described before. It varies from 1 to 5. Five (5) being the worst case scenario. In case of whole building analysis, degree of damage will be assigned to the overall building based upon the overall damage its elements have endured. Such figure of degree of damage may be allotted to the whole building after a systematic approach by team of experts. 83 6.1.5. Parametric mathematical model For deciding that whether replacement is a better option or rehab on technical ground (excluding the financial factor), following mathematical model will prove to be a handy tool. Above described factors C, D, T and L are considered in it. Now as stated several times that every case is a unique case and exhibits unique properties and have certain requirements. Moreover expectations varies from case to case and so does goals and aims. Some cases demands durability for which Life expectancy of solution “L” becomes the most important factor of all , others may consider time for building to continue its normal function as most striking factor of all e.g. in case of city’s main train station or airport building etc. Therefore, each case is unique and importance of factors (C, D, T, L) is unique too. Hence an importance factor “I” is multiplied with those factors to decide the contribution of each factor into results of mathematical model analysis and ultimately the decision making process. Importance factor “I” has unique value for each factor (C, D, T, L) such that their collection sum is equal to 1. It follows the following condition I = I 1 + I2 + I 3 + I4 = 1 For comparison and decision making following mathematical model is used. For both rehab and repair same mathematical model is used. Degree of damage will remain same for rehab and repair. Other factors like Life expectancy, Complexity and Time for proposed solution will differ depending upon respective solutions. As the result, of the solution of this model, a figure will be obtained called Feasibility Index (F.I). For both rehab and reconstruction, F.I will be obtained and one with lower F.I will be the preferred option. One more thing to notice is C, D and T are making positive contribution while L is making negative contribution in the model given below. Reason for that is, higher value of D, C and T will have opposite effect than higher value of L. higher value of C, D and T is a negative thing while more life is a positive thing. As they are having opposite effects, therefore they are making opposite contribution to the sum and this is also the reason for selecting the measure with lesser accumulated/sum value. It will be 84 more clarified in 6.2, where this mathematical model will be tested on a case study F.I = (C × I1) + (T × I2) + (D × I3) – (L × I4) 6.1.6. Example Calculation To understand the working and methodology of the mathematical model developed for technical feasibility and we will use a case study presented by Fay Engineer. The basic information about the case is as follow. Coal Coating Manufacturing Facility that has been built in 1956. Single floor building has area of 59,032 sq. ft. Roof structure has been damaged. Details about roof are128 Figure 22: KBP Coil Coaters129  Valley-Ridge geometry mild reinforced cast-in-place concrete folded plate  roof structure  Longitudinal span = 85 ft. with 9 ft. Cantilever  Valley to ridge height = 8 ft. and 8 in.  Reinforcement = Grade 40 Slab thickness = 3.5 ft. Details of damage to roof structure are as follow 128 Fay Engineering. 2003. KBP Coil Coaters Fire Repair and Shear Strengthening. Ppt. (http://www.fayengineering.com/articles/repair-fire-damaged-building-case-study accessed 5.8.14). 129 Fay Engineering. 2003. KBP Coil Coaters Fire Repair and Shear Strengthening. Ppt. (http://www.fayengineering.com/articles/repair-fire-damaged-building-case-study accessed 5.8.14). 85 Not whole roof structure was damage. Some valleys observed worst damage. Three Valleys with total area of 66ft. × 85 ft. beard most severe damage. The feature of damaged area are   For Concrete Visual Inspection: Colour is Buff to pink, Cracks along the reinforcement bars, Crazing is apparent on surface, Concrete spalls are apparent as well. Degree of damage verdict (Table 5) = 3 to 4  Core sampling and testing: Reduction in modulus of elasticity of concrete = 25 % Reduction in compressive strength of concrete = slight loss in comparison of undamaged concrete Degree of damage verdict = 3  Rebound hammer results: Shows different values of rebound number ranging from 28 to 37 Degree of damage verdict (Table 8) = 3 to 4 Petrographic Analysis Results: Shows Depth of damage upto 1.25 ft. or approx. 32 in. with surface temperature is concluded to be reached upto 1100 F or approx. 593 C. Radical cracks are around reinforcing bars. Loss of bond between reinforcement and concrete is around 30% to 50% Degree of damage verdict (Table 1, 5, 8) = 3 to 4    For Reinforcement Steel Loss of strength= None Plastic Deformation= None Final Judgement over the structure’s integrity is found to be within 50 to 75 % within current code requirement. After observing all test results and giving more 86 weightage to more accurate tests such as petrography and core sampling and testing plus the healthy condition of steel, degree of damage is estimated to be 3. Only worrying point is the loss of bondage between concrete and steel ranging from 30 % to 50%. But it is not detrimental as it can be cured with bonding agents. Also considering the area of roof damaged in case of fire also has its impact in the final decision of degree of damage.130 Figure 23: Top view of damaged Valley- Ridge concrete roof 131 Complexity of repair is minimal as it wouldn’t ask for heavy machinery to operate and wouldn’t have any significant effect on adjoining members, hence allotting degree of complexity as 1 for repair. For partial removal of slab and then providing with a new slab will cause lot of problems. Slab has to be removed and re-casted. It will require very heavy machineries and expert crew which can use most advance technologies to deliver the results. Even if slab is re-casted into this ridge valley geometry successfully it will cause the problem of cold joint between new and old concrete. And most probably new steel column supports have to be provided beneath this new slab. Hence degree of complexity for partial demolition and partial reconstruction would be at-least 4. Hence verdict is Complexity for repair = 1 Complexity for partial demolition and reconstruction = 4 130 Fay Engineering. 2003. KBP Coil Coaters Fire Repair and Shear Strengthening. Ppt. (http://www.fayengineering.com/articles/repair-fire-damaged-building-case-study accessed 5.8.14). 131 Fay Engineering. 2003. KBP Coil Coaters Fire Repair and Shear Strengthening. Ppt. (http://www.fayengineering.com/articles/repair-fire-damaged-building-case-study accessed 5.8.14). 87 Life expectancy for new slab would be at-least 50 years. Whereas for repaired slab with Glass Fibre Epoxy Composite Reinforcing, epoxy injections for epoxy inject cracks and Shot Crete would be around 20 years. Life expectancy for repair = 20 years Life expectancy for Partial demolition and reconstruction = 50 years. Time required for partial demolition and reconstruction depends upon no of daily site hours, efficiency of labour and management. Considering normal circumstances, it can be estimated to be around 100 to 150 days. In actual repair project, it took almost 4 months but considering this time to be bit too much and with proper management it could be done easily done within half of the period. Hence Time required for repair = 60 days Time required for partial demolition and reconstruction = 120 days Importance factor will be considered as 0.25 for all four factors to obsolete its effect, because data regarding the importance of factors is missing. Hence considering all four factors as equally important. But in cases, the importance factor can be divided according to the wishes of the decision makers depending upon the circumstances and goals. Now calculating F.I  For Rehabilitation and retrofitting (F.I)R&R = (C × I1) + (T × I2) + (D × I3) – (L × I4) (F.I)R&R = (1 × 0.25) + (60 × 0.25) + (3 × 0.25) – (20 × 0.25) (F.I)R&R = 11  For partial demolition and reconstruction (F.I)D&R = (C × I1) + (T × I2) + (D × I3) – (L × I4) (F.I)D&R = (4 × 0.25) + (120 × 0.25) + (3 × 0.25) – (50 × 0.25)  Conclusion (F.I)D&R = 19.25 As (F.I)R&R < (F.I)D&R 88 Hence Rehabilitation and retrofitting is more suitable than demolition and reconstruction, based on technical ground only, in this case. Now, let’s consider a phase where durability of the solution is the most important factor and complexity, Time required for proposal to execute and degree of damage are not that important and have equal weightage in sight of owners. Then I4 = 0.7 ; I3 = 0.1 ; I2 = 0.1 ; I1 = 0.1  For Rehabilitation and retrofitting (F.I)R&R = (C × I1) + (T × I2) + (D × I3) – (L × I4) (F.I)R&R = (1 × 0.1) + (60 × 0.1) + (3 × 0.1) – (20 × 0.7) (F.I)R&R = -7.6  For partial demolition and reconstruction (F.I)D&R = (C × I1) + (T × I2) + (D × I3) – (L × I4) (F.I)D&R = (4 × 0.1) + (120 × 0.1) + (3 × 0.1) – (50 × 0.7)  Conclusion (F.I)D&R = -22.3 As (F.I)D&R < (F.I)R&R Hence, demolition and reconstruction is more suitable than Rehabilitation and retrofitting based on technical ground only in this case. Reason is the shift of goal. In this case durability becomes more important than others hence putting the case in favour of demolition and reconstruction. 6.2. Financial feasibility analysis tool Debate over financial feasibility study has been much covered in literature theory. But as a matter of fact none of the conventional analysis methods like payback period, NPV and IRR actually sits well with the mathematical model presented before in 6.1. There are obvious limitations of these analysis tools/methods that makes it unfeasible for the financial feasibility analysis. Moreover, these shortcomings will reflect heavily in the mathematical model results as well if they will reside in financial analysis. There is a need for a financial analysis tool that can accurately compare complex and inconsistent proposals. Reason for that is 89 the proposed solution we have for redevelopment (rehab or reconstruction) of fire damaged building are not having consistent parameters. Their respective life spans and may differ. Similarly, their imposed tax rate may also vary. After consulting the limitations of many financial analysis methods for investment feasibility, it has been identified that Annual equivalent worth method can somehow do the job if properly modified for including financial factor in parametric mathematical model. It doesn’t have the limitation of same time period as required by NPV. It is more easily understandable as it excludes the time factor from the group of time, money and risk. This simplicity and accuracy is exactly what is required to be consistent with the mathematical model. AEW method is also consistent with NPV method. After all these advantages and suitability for financial evaluation of proposals concerning fire damaged buildings, still modifications are required. So the financial analysis tool used here has the same philosophy as AEW but has its own structure for better compatibility with parametric mathematical model and inclusion of risk factor in it. The financial analysis tool is described in detail below. There are many factors which have their say in technical feasibility. Similarly in financial feasibility there are many factors which contributes their share and must be included. Principal five factors on expense side that have their say in financial feasibility are 1. Depreciation (which is based upon the useful life of the building) 2. Interest rates 3. Taxes 4. Insurance costs 5. Maintenance and operation costs All these expenses are accumulated over the years and not always linear as well. But for ease, they are considered to be linear (constant average is used). An additional principal factor for rehab is fixed cost which may be present in some cases. It will be explained later. As finances will be provided as an investment therefore return of investment is also expected. Income factor is then included in 90 the financial feasibility analysis to calculate the difference between income and investment that will eventually establish the profit or loss. Each factor included many perspectives of financial considerations and collectively decides for the financial feasibility of the proposal. Both rehab and reconstruction proposal are financially analysed on annual basis and the better option with greater financial benefit is identified. 6.2.1. Depreciation The total cost of construction or rehabilitation is regarded as capital cost and as this cash is fixed in shape of a fixed asset (building) hence not in circulation anymore. The asset will be depreciated with the passage of time. This is all but natural process. The value to fixed asset decreases over the years. The factor which decides the annual rate of depreciation is the life of the building. There are different lives of the building depending upon the definition. Life of the building that is used in here is the useful life of the building. It is the life for which building remain economical and physically sound to carry out its intended function. The depreciation of assert is zero percent in the beginning means building investment hold its full capacity without losing a penny due to depreciation. In the end of useful life the depreciation is 100% which means building investment is totally diminished. Useful life is also known as write-off life. It is not the actual life of building but more like an analytical tool. It is an assumed figure in the financial calculation. Realistic approach must be used to determine this life. Following consideration must be considered while allotting useful life to the building as well.   It must be lesser than physical and economic life of the building In case of mortgage, it must not be lesser than loan period. It is described in units of years. In other words, it is the number of years over which the initial investment is spread out. Depreciation is presented in units of 91 percentage. The percentage value of depreciation is measured by the following formula Rate of depreciation = 100 / Useful life of building For a reconstructed building whose useful life is determined to be 30 years, now rate of depreciation would be 100/30 = 3.33%. This is the case of demolition and reconstruction. For rehabilitation and retrofitting, the useful life would start from the point of rehabilitation and reconstruction. For example, a ten year old building is damaged by fire, due to the investment on rehab, building’s write-off life or useful life of building is determined to be 12 years. It means that for next 12 years building will serve its function economically and fulfil above mentioned criteria. 6.2.2. Maintenance and Operation Maintenance and operation are the running costs of the facility. Every now and then building has to undergo routine maintenance and minor repair to keep it functionally astute and to safe guard its expected life. Maintenance costs are important factors and can’t be ignored. Although maintenance and operation costs are not uniform over the life span of the building. In some years it is less and in others higher. But usually they are taken as uniform average over the life span of building and vary from 1% to 3 % of total construction cost132&133. Some unusual cases of big repairs are not part of this percentage figure. 6.2.3. Interest Interests are applicable on every investment. If money is loaned from the bank then interest has to be paid. If own investment is used still cost of interests are incurred because investor is missing the money that he may earn by investing the money in the bank and can have immediate return on investment without 132 133 Joel Levitt. Evaluating Real Costs for Building Maintenance Management. Page no 1-2. http://realestate.msn.com/article.aspx?cp-documentid=25490855 accessed 20.08.2014. 92 moving a muscle. Interest cost are there and it is quite tricky to calculate interest cost incurred in the total expenses. It vary from one scenario to another scenario. A scenario is, where building is rehabilitated and the other is where building is reconstructed after demolition. Plus what is going to happen with the building afterwards. Will it be sold or used or rented out. Moreover what are the conditions of mortgage if loan is issued form the bank. Should the investor pay fix amount over a decided period of time or compounded interest will be returned back. Therefore interest cost have to be independently calculated but should be included in investment calculation to reflect the true picture of the investment. Interest is applied over average capital cost134 or interest rate can be halved and then applied over the full capital cost. Interest is applied for the duration of useful/write-off life of the building. 6.2.4. Tax Tax are applied in some cases. Specially the cases where demolition and reconstruction is involved. Tax rules differs from area to area and need to be accessed by fiscal experts to determine that how much taxes will apply on the proposal (if any). Cases where taxes are not involved and doesn’t accumulate in the expenses, there they are taken as zero. 6.2.5. Insurance Buildings are insured against damages for example fire damage insurance or flood insurance. In those cases where owner doesn’t go for any kind of insurance, still these insurance cost have to be included in the annual costs as risks of future hazards can’t be ruled out and this cost will act as risk management. Although, in certain cases and in certain areas it is mandatory to have insurance against fire and such hazards. So simply this factor can’t be ignored and should be counted in financial analysis. Usually insurance costs vary depending upon the design and material of construction and other such contributing factors. Usually, in 134 Capital cost loaned from the bank is paid off gradually hence the interest-able amount is full in the beginning and zero at the end. 93 general, insurance rates fluctuates from 0.5 % to 1 % of total construction cost in rural areas and 1% to 2% of total construction cost in urban areas135. For some special cases like flood prone or wild fire prone or earthquake prone areas or areas prone to other natural hazards, insurance rates are much higher. Building condition has a significant role to play in it. So this figure may jump from this general valuation of insurance costs. 6.2.6. Special Costs Costs of all above described factors are the principal costs. Except these costs sometimes there are some special costs. Although, it would be a rare incident but if there is some special cost are involved then they have to be added on expense side. If there are no such costs then it would be regarded as zero. 6.2.7. Annual Costs All the above mentioned costs collectively decides for the annual costs of the proposal which comes out in shape of percentage of total cost incurred for the specific proposal. For example if there is a building that has been damaged by fire and total cost (capital cost) of demolition and reconstruction is 10000 Euros. The useful/write-off life of building after reconstruction is considered as 25 years. The rate of depreciation would be 100/25 = 4%. Interest rate applied over the average capital cost or half interest rate applied over full capital cost gives same results. Therefore to make it compatible with other cost factors that are applied over capital cost, we will take half interest rate 5/2 = 2.5%. Considering there are 1% maintenance and repair charges, 0 % taxes and 1 % insurance cost. Therefore annual cost would be as given on the next page. 135 http://thelawdictionary.org/article/what-is-the-average-annual-cost-of-homeowners-insuranceand-property-taxes-for-florida-residents/ accessed 20.08.2014. 94 Depreciation Rate 4% Tax Rate 0% Insurance 1% Interest rate (avg.) 2.5% Operation and Maintenance rate 1% Total annual cost (% of capital cost) 8.5% 6.2.8. Annual income Total expenses are determined and have to be compared with the total income of the proposal that is under observation. Annual Income represents the total income generated from the facility after investment on yearly basis. In cases, where building is rented out, calculating annual income is pretty much straight forward business. In these cases simple total monthly rental income after taxes is multiplied with 12 to get the final annual rental income but that’s not always that simple and straight forward. In case, where owner has decided to sale out the building after it is being rehabilitated and retrofitted from fire damage gives a twist to the situation. In such cases, total annual income is calculated by dividing the total selling price after taxes and commission by the useful or write-off life of the facility (same as used for calculating depreciation). The total annual income mechanism would be elaborated later. 6.2.9. Working methodology and example After total annual cost in term of percentage of capital cost is determined and total annual income is determined. Difference between them can be easily calculated to determine annual profit or loss. But that’s not it. Debate over more sensible investment or decision making should include risk factor as well. General rule of thumb is more risk means more profit. A sensible investor doesn’t accept greater risk if he can’t see greater profit. Now how much one can gamble? And the 95 comparison between rehab and reconstruction upon basis of financial feasibility preferably should involve risk factor as well. Profit percentage obtained from both options can be corrected for risks involved. For example. If capital cost for reconstruction after demolition is 1,000,000 Euros and total annual cost is 8.5% (as shown in section 6.2.7). The total annual income from rent is 90,000 Euros. Then profit percentage would be Total annual cost = 8.5% of 1,000,000 = 85,000 € Total annual income = 90,000 € Annual Profit = 5,000 € Percentage profit (P.P) = 5,000/85,000 = 5.88 % Now, consider the second option of rehabilitation and reconstruction. The total cost over rehabilitation and reconstruction is calculated to be 400000 €. Almost one third of what has been proposed to spent on demolition and reconstruction. But, the useful life or write off life for retrofitting is determined to be max 10 years. So depreciation rate would be 100/10 = 10. Moreover, insurance rate will be more for rehabilitated and retrofitted building than the insurance rate of new construction with better fire design. Conclusively. Annual costs would be as follow Depreciation Rate 10% Tax Rate 0% Insurance 2% Interest rate (avg.) 2.5% Operation and Maintenance rate 1% Total annual cost (% of capital cost) 15.5% Total rental income can’t be expected to be as high as it would be in demolition and re-construction. Here let’s assume that rental income would be 75000 € Total annual cost = 15.5% of 400,000 = 62,000 € Total annual income = 75,000 € 96 Annual Profit = 13,000 € Percentage profit (P.P) = 13,000/62,000 = 20.97 % Hence in this case profit percentage indicates that retrofitting is a better option. But it is not as simple as it seems. In real world we have risks that have their telling factor in decision making. So risk factor should be considered in financial feasibility analysis. Investments in which pay back periods are longer, risk is usually higher than the investments where pay back periods are shorter. Many risks are covered upto an extent by insurance but still there are many risks that are not even covered by insurance. In above case, if retrofitting measure that was possible is not very reliable and there is high risk attached to its seismic performance then situation may differ. To normalise the profit percentage with inclusion of risk degree of risk can be introduced in financial feasibility analysis. Risk factor (R.F) may range from 1 to 5 with 5 being the case with minimum risk and 1 being the maximum risk. R.F = 1 to 5 (1 = maximum risk; 5= minimum risk). Risk factor (R.F) is multiplied with percentage profit (P.P) to obtain financial feasibility Score (F.F.S). The proposed solution with more value of F.F.S will be financially more feasible. F.F.S = R.F × P.P Now again consider the case showed in example. The retrofitting option that was the only way to retrofit and rehabilitate the building, carry risks of again serious damage to structure in case of any seismic activity. Unluckily the building is located in high seismic zone. Therefore risk factor is fixed as 1. While in case of demolition and reconstruction new design takes care of seismic issue and assure good performance over any such event thus the risk factor is decided to be 4. Now calculating financial feasibility score for both cases For Retrofitting (F.F.S)R&R = 1×20.97 = 20.97 For demolition and reconstruction (F.F.S)D&R = 4×5.88 = 23.52 97 Hence, final results shows that demolition and reconstruction seems to be more viable option in F.F.S. but this is highly subjective. Some investors like risk and are glad to take them while others don’t. So to include Risk factor in financial feasibility factor in analysis is totally upto the choice of the decision makers or analysts. 6.3. Feasibility analysis tool After technical and financial feasibility analysis, we are at the point where we can determine the overall feasibility of each proposal presented on the desk. With the addition of financial feasibility in the parametric mathematical model of technical feasibility, we can determine total or overall or simple feasibility analysis. Financial feasibility score (F.F.S) or Profit percentage (P.P) can be used in mathematical model to include financial factor in analysis. The final shape of mathematical model would be as follow F.I = (C × I1) + (T × I2) + (D × I3) – (L × I4) – (F.F.S × I5) Or F.I = (C × I1) + (T × I2) + (D × I3) – (L × I4) – (P.P × I5) Whereas; F.I = Feasibility index C = Degree of Complexity T = Time required for proposed solution D = Degree of damage L = Life expectancy of proposed solution F.F.S = Financial feasibility score P.P = Profit percentage I = Importance factor I = I1 + I2 + I3 + I4  I5= 1 98 Resultant of mathematical model is calculated and the proposed solution with lesser value would be regarded as more feasible solution. Summary Feasibility analysis tool that is developed as the part of solution development addresses the issue concerning decision making process. As it brings lot of ease and inherent characteristic to cover almost all factors that must be considered in decision making. But it can’t be granted with final authority as it has been very much in development phase. Its Alpha version is ready to be tested as Beta version. Repeated and rigorous testing with improvement is required to make it better and more efficient in a cyclic manner. Yet, this model is good enough to give a clear enough idea about the feasibility of proposals presented on the desk. As it has a philosophy to quantify parameters that usually can’t be quantified and then it uses those figures to draw a comparison. The philosophy integrated in the feasibility analysis tool for comparison between rehab or demolition and reconstruction cover almost all corners. It is because it dictates a system that starts with proper condition survey and condition assessment (deciding “D”), then it progresses towards technical and financial assessment of proposed solutions (deciding “C, T, L” & “F.F.S, P.P”) for the case on hand. Then it includes the impact of factors that has its say in the decision, by the help of importance factors and allots them their respective share in decision making which is often quite vague and unclear. 99 7. Trial of feasibility analysis tool The case used here for elaborating the validity of mathematical model and its understanding, is located in Islamabad, capital city of Pakistan. The building is a commercial shopping mall with some office space as well. Building originally got damaged by fire and then rehabilitated. We will test our mathematical model over it. As this building has been retrofitted and rehabilitated instead of demolition and reconstruction therefore we already know the right choice. If our model favours the same solution and consider it a better option, then it can be interpreted that model works fine and can be used for feasibility study or comparison studies. The data about the case is as follow. Name of the building: Beverly centre Islamabad Location: Jinnah Avenue, Sector F-6, Islamabad. Overall area: 365,904 square feet (approx.) Floor: Basement+5 Floors (total 6 floors) Figure 24: Beverly Centre Islamabad136 A fire broke out on Sunday, 16 January, 2011 at about 2030 hrs on the Eastern side of 4th floor. The fire spread up to 5th floor when it was extinguished after approximately 9 hrs at 0545 hours on 17 Jan 2011 as per the statements of the 136 Courtesy of Syed Ameer ul Hassan. Sub Divisional Officer in Communication and Works department. Govt. of Punjab. Pakistan. 100 eye witnesses interviewed and fire department report. As a result top two floor of building has undergone heavy damage. Approximately most of the building interior in top two floors was damaged and un-useable. HVAC had undergone critical damage as well. Structure somehow has retained its integrity as luckily building lies in high seismic zone so design was having extra capacity. Moreover columns were jacketed with concrete to give it some extra strength and seismic capacity as well. This concrete jacket worked as extra cove and protected the structural member too. Figure 25: Fire damaged Beverly Centre Islamabad137 The structure has been evaluated at first with different testing techniques and found out to have its structural strength more or less intact while most of the building equipment and HVAC got damaged. Figure 26: Burnt AC unit (left), Damages Electricity cables (right)138 Results of diagnosis of Beverly centre dictates following facts  The Beverly Centre did not undergo major structural damage due to the fire, erupted on top two floors. 137 Courtesy of Syed Ameer ul Hassan. Sub Divisional Officer in Communication and Works department. Govt. of Punjab. Pakistan. 138 Courtesy of Syed Ameer ul Hassan. Sub Divisional Officer in Communication and Works department. Govt. of Punjab. Pakistan.  101 Fire affects mainly consist of calcinations of concrete blocks used for floor system construction between the ribs and the concrete cover for the ribs,  solid slabs, columns and shear walls. The bottom steel reinforcement in the ribs does not have adequate bond with concrete at a number of locations due to improper detailing and poor  concrete quality. A few concrete blocks between the ribs fell down during the fire action. However blocks neither fell nor cracked during the load test which indicates adequate integrity of these blocks with the floor structure.139 Hence, Degree of Damage (D) = 3 To demolish top two floors and then to rebuild it takes time. According to current practices the time estimates for reconstruction is about 5 months or 150 days. Lack of the possibility to use heavy machinery in the highly commercial area makes demolition and reconstruction slower. Whereas, retrofitting the structure and rehabilitating of building has been scheduled for 70 days 140. One factor for slow repair was also the working hours of the site. Hence Time (T) for Rehabilitation and Retrofitting = 70 days Time (T) for Demolition and Reconstruction = 150 days To demolition the whole upper two floors of the building and then provide with a new one doesn’t impose any certain complexity. It would be pretty much straight forward and standard process. Whereas retrofitting a fire damaged structure that has been retrofitted for seismic activates is not as simple as it seems. But yet there has not been any striking or challenging situation except in designing for following measure that have been taken to rehab the top two floors of the building. These remedial measures are given below. 139 Courtesy of Syed Ameer ul Hassan. Sub Divisional Officer in Communication and Works department. Govt. of Punjab. Pakistan. 140 Courtesy of Syed Ameer ul Hassan. Sub Divisional Officer in Communication and Works department. Govt. of Punjab. Pakistan.   102 Remove the concrete blocks, provided in between the ribs of the floor system  Loose concrete around the rib bottom reinforcement should be removed  procedure  sure that appropriate quality assurance procedures are followed The ribs should be properly concreted with shotcrete, using dry or wet The seismic retrofitting, as already designed, should be redone making The upper two stories are considered softer as compared with the other floors. Solid partition walls may be provided between the columns to  enhance the lateral stiffness of the structure The foundation structure is relatively flexible and needs to be stiffened for the seismic performance requirements. Hence, For Rehabilitation and Retrofitting Degree of Complexity (C) = 3 For Demolition and Reconstruction Degree of Complexity (C) = 2 Expected life of new floors that has been built after demolition must have considerable more life than reconstructed or patched one, especially, in the area which is active in terms of seismic activities. Moreover it is a commercial building so expected life for both proposals are as under. For Rehabilitation and Retrofitting Life expectancy (L) = 10 years For Demolition and Reconstruction Life expectancy (L) = 25 years Calculation of financial feasibility are bit tricky considering some assumptions. For rehabilitation of building and retrofitting of structure data is available but not for reconstruction and demolition141. So market rates and local rates of the area have been used for calculation. 141 Because actual measure to bring building back to its functional state was Rehabilitation and retrofitting.  For Retrofitting and Rehabilitation Depreciation Rate 10% Tax Rate 2% Insurance 2% Interest rate (avg.) 4% Operation and Maintenance rate 1% Total annual cost (% of capital cost) 19% 103 Write-off life is considered same as life expectancy, so depreciation rate would be 10%. Normal interest rate is 8% in commercial mortgage hence we use half (4%) of it but on full investment (reason explained in section 6.2.3). Total cost of rehabilitation and reconstruction = 100,912,000 PKR142 Total cost of rehabilitation and reconstruction = 763906.13 € 143 Total annual cost = 0.19 × 763906.13 € = 145142.165 € = 145142 € Total annual income = 6 €/year/sq. ft. × 0.55 × 121968 sq. ft. = 402494 € Here 6 € is the yearly rental rate for one square foot. 121968 is the total floor area of top two floors. 0.55 is the percentage of total rentable space on 3 rd and 4th floor144. It is calculated as explained on next page Average monthly rent of the space on 4th and 5th floor fluctuates between 50 to 82 PKR per square feet per month depending on market and location factors 145. So taking the mean value of 66 PKR per square feet per month. So, monthly per square feet rate of rent = 66 PKR 142 Actual cost. Conversion rate is Forex exchange rate 08.09.2014 (17:32 GMT1). 1 Euro = 132.1 PKR. 144 Actual space that can be rented. Total space on 2 floor excluding construction, stair, cases, lobbies etc. 145 Current market Rates 22.08.2014. 143 104 Annual per square feet rate of rent= 66 × 12 PKR =792.6 PKR =6.001146 € or 6 € Total area of 6 floors = 365904 sq. ft. Area of 2 floors = 365904/3 = 121968 sq. ft. Difference between total annual cost and income = 402494  145142 =257352 € Profit Percentage (P.P)R&R = 257352 / 145142 = 177.3% 147 Risk is higher in Retrofitting and reconstruction as there is a possibility of some unidentified errors or damages that remain untreated. Moreover, errors in design that is complex in nature or errors in workmanship can have its impact. Plus the structure is situated in high seismic zone. Bigger shocks comes few and far but smaller shocks are matter of routine. These smaller shocks are not only responsible for shorter life expectancy but high risk too. As insurance service doesn’t cover for wars, civil disobedience, protest damages or damages due to movement of earth e.g. landslides, earthquake sink holes etc. This case is subjected to serious earthquake risk in retrofitted condition if an earth quake of Richter scale 6.5 or higher will come. Hence value of risk factor could be 2 (R.F)R&R = 2 So, (F.F.S)R&R = (R.F)R&R × (P.P)R&R (F.F.S)R&R = 2 × 177.3 (F.F.S)R&R = 354.6  For Demolition and Reconstruction 146 147 Depreciation Rate 4% Tax Rate 2% Insurance 1% Interest rate (avg.) 4% Conversion rate is Forex exchange rate 08.09.2014 (17:32 GMT1). 1 Euro = 132.1 PKR It is not actual profit percentage (see 2nd paragraph of Summary (financial feasibility)). 105 Operation and Maintenance rate 1% Total annual cost (% of capital cost) 12% Write-off life is considered same as life expectancy, so depreciation rate would be 4%. Normal interest rate is 8% in commercial mortgage hence we use half (4%) of it but on full investment (reason explained in section 7.3). Insurance rate will be lesser because of better design against fire and earthquakes. Total cost of Demolition and Reconstruction = 121968 sq. ft. × 4000 sq. ft. = 487872000 PKR148 Here 121968 is the total floor space of 2 floors and 4000 is the construction cost of 1 sq. ft. Total cost of Demolition and Reconstruction = 3693202 € 149 Total annual cost = 12% × 3693191 = 443184.25 € Total annual income = 7.5 €/year/sq. ft. × 0.6 × 121968 sq. ft. = 548856 € Here 7.5 € is the yearly rental rate for one square foot. 121968 is the total floor area of top two floors. 0.6 is the percentage of total rentable space on 3 rd and 4th floor150. Efficiency of design can improve from 0.55 to 0.6 in new design with use of slender structural members and eliminating the need of jacketing. Difference between total annual cost and income = 548856  443184.25 = 105672 € Profit Percentage (P.P)D&R = 105672 / 443184.25 = 23.84% 151 As new design can improve the risks attached to the building as explained earlier hence maximum protection can be insured. But still building lies in active seismic zone therefore (R.F)D&R = 4 So, (F.F.S)D&R = (R.F)D&R × (P.P)D&R 148 Market price ranges from 2500 to 5000 PKR per sq. ft. in the area for commercial construction. Conversion rate is Forex exchange rate 08.09.2014 (17:32 GMT1). 1 Euro = 132.1 PKR. 150 Actual space that can be rented.Total space on 2 floor excluding construction,stair,cases,lobbies etc. 151 It is not actual profit percentage. 149 106 (F.F.S)D&R = 4 × 23.84 (F.F.S)D&R = 95.38 Now, F.I = (C × I1) + (T × I2) + (D × I3) – (L × I4) – (F.F.S × I5) Importance factors are assigned according to the demands of the building, as it is a commercial building hence finance will get maximum share. Second most important factor would be life expectancy from investor or owner point of view. Time required for the building to come back to its original condition will obviously be important too as it’s a loss to the business concerning 4th and 5th floor and also to the floors beneath. Complexity might not be that much important factors for owner who has maximum involvement in decision making. Moreover in this case, there are no such serious complications neither in rehab nor in reconstruction. Degree of damage is not serious but intermediate and manageable so from technical point of view it’s not that problematic. Plus from owner or investor’s point of view, it has less importance too. As far as building can be restored to its functional level, owner will be satisfied with this. Hence following distribution of importance factor is rational. I1 = 0.03; I2 = 0.2; I3 = 0.07; I4 = 0.25; I5 = 0.45 Now putting all these values in mathematical model will give F.I values.  For Rehabilitation and Retrofitting F.I = (C × I1) + (T × I2) + (D × I3) – (L × I4) – (F.F.S × I5) F.I = (3 × 0.03) + (70 × 0.2) + (3 × 0.07) – (10 × 0.25) – (354.6 × 0.45) (F.I)R&R = 147.77  For Demolition and Reconstruction F.I = (C × I1) + (T × I2) + (D × I3) – (L × I4) – (F.F.S × I5) F.I = (2 × 0.03) + (150 × 0.2) + (3 × 0.07) – (25 × 0.25) – (95.38 × 0.45) (F.I)D&R = 18.9 107 As, (F.I)R&R < (F.I)D&R Hence Rehabilitation and retrofitting is a better option According to the feasibility analysis done by our model, Rehabilitation and retrofitting is better option than demolition and reconstruction. Actual case has been rehabilitated and retrofitted as well, therefore validity of the model is proved. This case may not be a very complex case. In tight cases, this mathematical model can really prove to be a handy tool if accurate data is provided and importance factors are rightly accessed. 108 8. Conclusion, scope, recommendation, critique & summary of study 8.1. Conclusion Risk of fire is always there for all kind of buildings. Concrete buildings are no exception to it. Though concrete buildings are more resilient to fire than others but a serious fire can inflict damage which depends upon salient features of fire and building. After fire is extinguished and structure is secured, condition survey and condition assessment is done over it. Condition survey is done by a team of experts. Visual inspection, hammering and chiselling techniques are used for condition survey. It gives basic idea about the building condition. Afterwards condition assessment is done, if it is felt to be required. In condition assessment, different tests are conducted and their values are recorded, to access the true condition of building. Different non-destructive testing and destructive testing techniques are used like Schmidt hammer test, UPV test, penetration resistance test, core sampling and testing, petrography, deflection test, tensile test and SEM microscopy. There are lot of other testing techniques available to serve the cause but these techniques are selected after careful selection on the bases of purpose, economy, availability, accuracy, efficiency and damage to the building and environment. Use of NDTs for evaluation of concrete strength is beneficial but comes with accuracy of 65% to 85% (if properly conducted). More accurate and detailed techniques like core sampling, tensile test and petrography are bit costly. So only to be used when necessary. To determine that whether building should be demolished and reconstructed or rehabilitated and retrofitted, comprehensive feasibility study (technical & financial aspects) should be conducted. Technical aspect is determined from the data obtained from evaluation of fire damaged building whereas financial aspect is based upon financial analysis tools and risk analysis. The financial analysis tools available for the financial analysis of proposed solutions are the same which are used for feasibility study of every other investment. But these financial tools have their limitations and are not completely compatible for the purpose. Hence a need has been there for a financial analysis tool that can be specifically used for fire damaged buildings. A feasibility analysis tool has been developed as part of 109 master thesis. It is expected to bring lot of ease in decision making process because of its detailed structure. But decision shouldn’t be made solely on its bases as it is not a war hardened horse yet. Repeated and rigorous testing with improvement is required to make it better and more efficient in a cyclic manner. Yet, this model is good enough to give a clear enough idea about the feasibility of proposals presented on the desk. It has a philosophy to quantify parameters that usually can’t be quantified and then it uses those quantified values in feasibility analysis tool as inputs. The philosophy integrated in the feasibility analysis tool for comparison between proposals (e.g. rehab or reconstruction) covers all important factors. It is because it dictates a system that starts with condition survey and condition assessment (deciding degree of damage “D”), then it progresses towards technical and financial assessment of proposed solutions (deciding “C, T, L” & “F.F.S, P.P”)152 for the case on hand. Then it includes the impact of factors by the help of importance factors and allots them their respective share in decision making which is often quite vague and unclear. Financial part of this newly developed feasibility analysis tool has the same philosophy as AEW (annual equivalent worth) method but has its own structure for better compatibility and inclusion of risk factor in it. Retrofitting and rehabilitation starts with cleaning activity, after it is established as a better option by feasibility study. Smoke and soot should be cleaned from the surface of building and belongings which would otherwise deteriorates them and smoke odour will be a permanent stay. Thermal foggers, ozone machines and air scrubbers are used to take care of smoke odour. Air scrubber is the safest option among them. Combustible non-structural members /parts of the building are often in poor condition and beyond repair so would be replaced. Generally, nonstructural members and utilities that are not much damaged needs surface treatments only. Soda blasting is good, sustainable, economical and effective technique for surface treatment. Patching and varnishing can also be done if required. HVAC, electrical wirings and other utilities can be repaired if damages are limited otherwise have to be replaced partially or completely. Structural members can be retrofitted by FRP reinforcing, partial removal and replacement 152 C: degree of complexity, L: life expectancy, T: time required, F.F.S: financial feasibility score, P.P: profit percentage 110 of damaged concrete and steel, concrete or steel jacketing and epoxy injections. FRP reinforcing technique is a good measure with many excellent advantages like performance, light weight etc. but falls short on the criteria of future fire proofing and sustainability. Partial removal and replacement is a sound technique for retrofitting and most popular one. It is a sustainable method with good fire proofing qualities but it might prove to be bit more costly than FRP. Partial removal can put extra stress on adjoining members hence needs propping. Concrete jacketing is used basically for earthquake retrofitting but can be used for fire damaged concrete buildings in certain cases. It is a fire proof and sustainable technique but may alter the structural behaviour of structure and dimension of members. Steel jacketing is more suitable than concrete jacketing for the purpose and it also doesn’t change the dimensions of members significantly. It is sustainable but needs protection from fire and rusting with a protective coating. Epoxy injections are used to fill cracks and to make up for the loss of bonding between steel and concrete. 8.2.   Recommendations Feasibility analysis tool should be used as a supplementary tool in decision making process, as it is still in development phase. Data required as the input in feasibility analysis tool should be carefully and thoughtfully collected. If assumptions are made then special care should be taken for more sensitive parameters indicated by sensitivity analysis. For each assumption three or more possible values should be  chosen to realise their impact. Importance factor must be decided by round table talk in which all project players and experts must participate. Again for evaluation of different scenarios two or three different values can be tested. This practice will  provide decision makers with the broader vision. More research is required on topic of feasibility analysis. This analysis tool provide a good foundation for feasibility study of proposals. In future, further work can be done to improve its accuracy and effectiveness 111 8.3. Scope The study provides with a system to take care of fire damaged concrete buildings. It encompasses evaluation, decision making (feasibility study) and rehabilitation of fire damaged concrete buildings. Findings of the thesis can be helpful for insurance companies, professionals of construction industry, banks/investors and especially fire rehabilitation companies. The study can contribute to the research that may be done in future on the topic. 8.4. Critique The study covers the whole process of dealing with fire damaged concrete building and able to equip its readers with good understanding. It develops a new tool for feasibility analysis that includes both technical and financial aspects. Hence, it will help its users in decision making, especially in those border line case which are complex. Study introduces a total new analysis tool for feasibility assessment of proposed solution for fire damaged concrete buildings but it is without any proven record as it is the case of all new tools. Hence can’t be readily used as independent decision making tool. Further improvement in structure and philosophy will improve its capacity and efficiency. 8.5. Thesis Summary Concrete buildings are damaged in the event of fire. Although, damage experienced by concrete buildings is much less severe than buildings having steel and wood as basic materials of construction. Yet severe fires can also cause serious damages in concrete buildings. The damage is not only caused by fire. Smoke, soot and water (fire extinguisher) all contribute their share. This study presents a structured solution to deal with fire damaged concrete buildings. Study categorizes the fire damage rehabilitation process of concrete buildings into three categories: evaluation (consists of understanding of material behaviour, condition survey and condition assessment), feasibility study (consists of technical and financial analysis), rehabilitation and retrofitting (consists of cleaning, soda 112 blasting, surface treatments, FRP reinforcing, Partial removal and replacement, concrete jacketing, steel jacketing, epoxy injections and others). In chapter 2, evaluation aspects of fire damaged concrete buildings are discussed. First two research questions have been answered in it.   How to conduct condition survey and condition assessment? What tests and field inspections are required? It explains that damage endured to concrete buildings depends upon many factors like design of building, scope of fire, temperature and duration of fire, etc. Nobody, should enter the building unless structure is secured and building got clearance from respective authorities. Concrete buildings are naturally much tolerant to fire, thanks to the fire proofing properties of concrete. In concrete buildings, mostly fire damage is retained by concrete cover and steel is escaped from damage. Desk study has to be done before evaluation of building, to understand salient features of building and fire. Condition survey is conducted on the building (for both structural and no structural members) to have basic understanding about degree of damage. It is done by means of visual inspection, hammer tapping and chiselling. Condition Assessment is conducted on structural members to precisely access their condition and to determine actual degree of damage endured. Mostly NDTs are practiced to find out the residual strength and stability of structure. Non-destructive test like Schmidt hammer, UPV test and penetration resistance test gives good idea about the structure’s residual strength, if they are conducted properly. They can’t be totally relied upon owing to their inherent shortcomings as none of them directly calculates the strength of concrete or steel. Instead, all NDTs uses indirect correlations to evaluate the certain criteria which is not necessarily be strength. To sum it up, NDTs results have 65% to 85% accuracy. They can serve up the purpose for some cases (especially those buildings which are not much damaged) but can’t be considered as authority. Cases, where better accuracy is required, core sampling & testing and petrography test should be conducted for evaluation of concrete. For steel, tensile test and SEM microscopy can provide accurate evaluation. Combination of core sampling & testing, petrography and tensile test is enough to thoroughly understand the condition of conventional R.C.C buildings. If pre-stressing is 113 involved then SEM microscopy may be added. The prices of these tests are higher in market than other conventional tests. Therefore should be conducted in case of necessity. Chapter no 3, describes the measures that are required for retrofitting and rehabilitation of fire damaged buildings including both structural and nonstructural parts. This chapter answers research question number 6 and 7, which are given below.  How to rehab the building (non-structural components)? What possible treatments are feasible in light of economy, sustainability, building  functionality etc.? How to retrofit structural components? What possible treatments are feasible in light of economy, sustainability, fire protection, building functionality etc.? Retrofitting and rehabilitation starts with cleaning activity, after it is established as a better option by feasibility study. Smoke and soot should be cleaned from the surface of building and belongings which would otherwise deteriorates them and smoke odour will be a permanent stay. Thermal foggers, ozone machines and air scrubbers are used to take care of smoke odour. Air scrubber is the safest option among them. Combustible non-structural members /parts of the building are often in poor condition beyond repair so would be replaced. Generally, non-structural members and utilities that are not much damaged needs surface treatments only. Soda blasting is good, sustainable, economical and effective technique for surface treatment. Patching and varnishing can also be done if required. HVAC, electrical wirings and other utilities can be repaired if damages are limited otherwise have to be replaced partially or completely. Structural members can be retrofitted by FRP reinforcing, partial removal and replacement of damaged concrete and steel, concrete or steel jacketing and epoxy injections. FRP reinforcing technique is a good measure with many excellent advantages like performance, light weight etc. but falls short on the criteria of future fire proofing and sustainability. Partial removal and replacement is a sound technique for retrofitting and most popular one. It is a sustainable method with good fire proofing qualities but it might prove to be bit more costly than FRP reinforcing. 114 Partial removal can put extra stress on adjoining members hence needs propping. Concrete jacketing is used basically for earthquake retrofitting but can be used for fire damaged concrete buildings in certain cases. It is fire proof and sustainable technique but may alter the structural behaviour of structure. It changes the dimension of members. Steel jacketing is more suitable than concrete jacketing for the fire retrofitting and it also doesn’t change the dimensions of members significantly. It is sustainable but needs protection from fire and rusting with a protective coating. Epoxy injections are used to fill cracks and to make up for the loss of bonding between steel and concrete. Chapter 5 describes the results and findings of the literature study done in chapter 2, 3 and 4. Literature study have been evaluated in this chapter. Problems that were associated with literature study and the area of knowledge that has been lacking in literature have been identified. Once problem is identified, its solution has been proposed. There are no research question that have been answered in this chapter. Chapter 4, 6 and 7 deals with feasibility study of different solutions that can be realised for the damaged concrete building to bring it back to its functional capacity. In feasibility study, both financial and technical aspects have been considered. This part of thesis answers research questions number 3, 4 and 5 as given below.   What can be done with buildings that are damaged because of fire (Demolitions, Re-use etc.)? Is it possible and feasible to retrofit the structural components and rehabilitate the building, concerning the damage they have endured  (Technical feasibility)? Is it financially feasible to retrofit and rehab the fire-damaged building? Chapter 4 describes that condition survey and condition assessment evaluates the condition of building. After evaluation it is required to decide about the fate of the concrete building. Both reconstruction and rehabilitation are possible in normal cases. To determine that whether building should be demolished and reconstructed or rehabilitated and retrofitted, comprehensive feasibility study 115 (technical & financial) should be conducted. For technical aspect of feasibility study, data obtained from condition survey and condition assessment is vital. Collected data is random and scattered so it must be properly structured and then analysed to help in carrying out technical feasibility studies. Financial aspect is very vital as well. In most of the business cases, it is the most important factor. Various financial analysis methods are used to understand the viability of investments i.e. payback period, IRR, NPV, MIRR etc. All these analysis methods are general purpose methods for calculating financial feasibility for all sorts of investments. But fire damage buildings are not ordinary case, here we need comparison between proposed solutions with certain eccentricities i.e. the time period of both investments (proposed solutions) may not be same, interest rate of investments may not be same as well etc. Due to limitations of conventional analysis methods like NPV, IRR, and payback period these methods are not always suitable for financial analysis especially in complex cases with inconsistencies. Risk analysis must be done in order to take into account the sensitivity of variables involved in financial analysis. So that more efforts can be concentrated over their estimation or procurement. Best and worst case scenarios are also determined by risk analysis. Chapter 6 explains that feasibility analysis tool that is developed as the part of solution development addresses the issue concerning feasibility study. As it brings lot of ease and inherent characteristic to cover almost all factors that must be considered in decision making. But it can’t be granted with final authority as it has been very much in development phase. Its Alpha version is ready to be tested as Beta version. Repeated and rigorous testing with improvements is required to make it better and more efficient in a cyclic manner. Yet, this model is good enough to give a clear enough idea about the feasibility of proposals presented on the desk. As it has a philosophy to quantify parameters that usually can’t be quantified and then it uses those figures to draw a comparison. The philosophy integrated in the feasibility analysis tool for comparison between rehab or reconstruction cover almost all corners. It is because it dictates a system that starts with proper condition survey and condition assessment (deciding “D”), then it progresses towards technical and financial assessment of proposed solutions (deciding “C, T, L” & “F.F.S, P.P”) for the case on hand. Then it includes the 116 impact of factors that has its say in the decision, by the help of importance factors and allots them their respective share in decision making which is often quite vague and unclear. Financial part of feasibility analysis tool has the same conceptual methodology as AEW (annual equivalent worth). AEW method doesn’t have the limitation of same time period as required by NPV. It is more easily understandable as it excludes the time factor from the group of time, money and risk. This simplicity and accuracy is exactly what is required to be consistent with the mathematical model. Although, AEW method is suitable for financial evaluation of proposals concerning fire damaged buildings, but can’t be used as it is. Modifications has been required to tailor fit it for financial analysis (of fire damaged building’s) needs. Therefore, financial part of feasibility analysis tool has been developed in such a way that it works on the principals of AEW but it has its own structure for the sake of better consistency with the feasibility analysis tool. It also included the risk factor to provide a combined assessment of investment including both profit and risks involved. The feasibility analysis tool (parametric mathematical model) is given below F.I = (C × I1) + (T × I2) + (D × I3) – (L × I4) – (F.F.S × I5) Whereas, F.I = Feasibility index, C = Degree of Complexity, T = Time required for proposed solution, D = Degree of damage, L = Life expectancy of proposed solution, F.F.S = Financial feasibility score, P.P = Profit percentage, I = Importance factor (I = I1 + I2 + I3 + I4  I5= 1). The parametric mathematical model includes technical aspect in term of D, C, T and L, whereas financial aspect is included in terms of F.F.S. Hence financial analysis tool compares the proposed solutions on both technical and financial grounds. Chapter 7, introduces a real life case study to test and to understand, the working method of feasibility analysis tool (parametric mathematical model). The case used here is commercial building known as “Beverly centre Islamabad” located in Islamabad, capital city of Pakistan. The building is a commercial shopping mall with some office space as well. It got damaged by fire and then rehabilitated. Mathematical model have been tested over it. As this building has been retrofitted 117 and rehabilitated instead of demolition and reconstruction therefore feasible solution has already been known. Efforts have been inducted to determine values of variables required for the feasibility analysis tool and more or less have been obtained. For few variables, estimations have been made. If, model declares the same solution more feasible, then it can be interpreted that model works fine and can be used for feasibility or comparison studies. Feasibility analysis has been conducted and it supported the same real life solution (Retrofitting and rehabilitation). Hence, argument of feasibility analysis tool’s performance and validity has been supported. Chapter 8 includes conclusion, recommendations, scope of thesis, critique and thesis summary. It answers last research question  What is the Scope of research findings/conclusions? 118 9. List of Literature AGI: http://www.agi.my/index.php/our-solutions/disaster-restoration/arestoration-services-include/stubborn-unpleasant-odor/thermal-and-misttreatment-to-remove-all-types-of-malodor/ (accessed 11.08.2014.) Barber hoffman: http://www.barberhoffman.com/portfolio/projectdetail.aspx?PortfolioID=113 (accessed 30.07.2014.) Björnsdóttir: Financial feasibility assessments: Building and Using Assessment Models for Financial Feasibility Analysis of Investment Projects. 2010 Building green: http://www2.buildinggreen.com/article/retrofits-usually-greener-newconstruction-study-says (accessed 10.08.2014.) Burgozne, Balafas: Why is FRP not a financial success?. 2007 Caltransd7info Blog Spot. De: http://caltransd7info.blogspot.de/2011_12_01_archive.html (accessed 31.07.2014) CCTIA: http://www.cctia.org/FAQ_Files/10.001_Concrete_Core_Tests.html (accessed 21.07.2014.) Ccw Online: http://www.ccwonline.com.au/prod437.htm (accessed 11.08.2014.) Chicora: http://chicora.org/fire.html (accessed 11.08.2014.) Clean Fax: http://www.cleanfax.com/articles/105969-effective-thermal-fogging (accessed 11.08.2014.) 119 Cleaners Coach: http://cleanerscoach.com/Media-Blasting.html (accessed 12.08.2014.) Composites Manufacturing Magazine: http://compositesmanufacturingmagazine.com/2010/08/pursuit-newfrpprotection-heats/ (accessed 15.08.2014.) Concrete UK: http://www.concrete.org.uk/fingertips_nuggets.asp?cmd=display&id=893 (accessed 11.07.14.) Corecut-jo: http://www.corecut-jo.com/index.php?module=services&id=6 (accessed 16. 08.2014.) CPWD, India: Handbook of repair and rehabilitation of R.C.C buildings. 2002 Concrete Society: Assessment, Design and Repair of Fire-damaged Concrete Structures. Technical Report No. 68. 2008 Department of Public health, Los Angeles County: How to clean up smoke and soot from a fire. 2013 EMS Sales: http://www.emssales.net/store/cart.php?m=product_detail&slug=predator -600-portable-air-scrubber. (accessed 11.08.2014.) Engineering Civil: http://www.engineeringcivil.com/visual-inspection-of-concretestructure.html (accessed 10.07.2014.) Engingeering Arhives: http://www.engineeringarchives.com/les_mom_tensiletest.html (accessed 26.07.2014) ESCA Blast: http://www.escablast.com/store.asp?pid=35117 (accessed 12.08.2014.) 120 Fay Engineering: KBP Coil Coaters Fire Repair and Shear Strengthening. 2003 Frbiz789: http://frbiz789.blog.com/2009/12/01/hydrodemolition/(accessed 15.08.2014.) Gbg. UK: http://www.gbg.co.uk/?page=strfirevissurv (accessed 29.07.2014) Haseeb Uz Zaman, Tahir Saleem, Azhar Shehzad, Mohsin Ashfaq & Muhammad Bilal: Comparison of compressive strength of concrete calculated by destructive and non-destructive testing. 2011 Helfert: Financial analysis tools and techniques: a guide for managers 1st edition. 2001. IstructE: Introduction to the fire safety engineering of structures.2007 Institute of Food and Agricultural Sciences, University of Florida: The Disaster Handbook National Edition. 1998. Ivan Detchev, Ayman Habib, Mamdouh El-Badry: Case study of beam deformation monitoring using conventional close range photogrammetry.2011 Jeremy P Ingham: Forensic engineering of fire damaged concrete structures. 2009 Joel Levitt: Evaluating Real Costs for Building Maintenance Management. 2003 JPCL: Surface Preparation of Concrete Substrates. 2011 121 Laura J. Powers: Petrography as a Concrete Repair Tool. 2002 Lee: Financial Analysis, Planning And Forecasting: Theory and Application, 2nd edition. 2009 Matson: U.S. Department of Agriculture; Rural Business-Cooperative Service, Service. Report 58: Vital Steps, A Cooperative Feasibility Study Guide. 2000 Martin Alberto Masuelli: Introduction of Fibre-Reinforced Polymers – Polymers and Composites: Concepts, Properties and Processes. 2013 Metrocorp: http://www.metrocorp.com.au/services-item.php?id=4(accessed 15.08.2014.) Michael Hayes: Rebuilding After a Fire. 2012 Park: Contemporary Engineering Economics. 3rd edition. 2002 Ponmalar: Strength comparison of Fibre Reinforced Polymer (FRP) wrapped concrete exposed to high temperature. 2012 Ramsetmbtmedan: http://ramsetmbtmedan.blogspot.de/2012/09/jacketing-struktur.html (accessed 18.08.2014.) Real estate Msn: http://realestate.msn.com/article.aspx?cp-documentid=25490855 (accessed 20.08.2014) 122 Shotcrete: http://www.shotcrete.org/pages/products-services/technical-questionsarchive.htm (accessed 16.08.2014.) Structure Mag: http://www.structuremag.org/?p=4102 (accessed 10.07.2014.) Sustainable Concrete: http://www.sustainableconcrete.org/?q=node/171 (accessed 16.08.2014) Syed Ameer ul Hassan: Sub Divisional Officer in Communication and Works department. Govt. of Punjab. Pakistan. Teran, Ruiz: Reinforced concrete jacketing of existing structures. 1992 The Concrete centre: Concrete and fire safety. 2008 The Concrete Portal: http://www.theconcreteportal.com/nde.html (accessed 11.07.2014.) The Constructor: http://theconstructor.org/structural-engg/strengthening-of-r-ccolumns/1935/ (accessed 18.08.2014.) The Law Dictionary: http://thelawdictionary.org/article/what-is-the-average-annual-cost-ofhomeowners-insurance-and-property-taxes-for-florida-residents/ (accessed 20.08.2014.) V.M. Malhotra, Nicholas J. Carino: Handbook on Non-destructive Testing of Concrete Second Edition. 2004. Wise Geek: http://www.wisegeek.com/what-is-an-air-scrubber.htm 11.08.2014.) (accessed 123 Youtube: https://www.youtube.com/watch?v=bZuks_1SdCI (accessed 15.08.2014.) Zizzo: Life cycle costing: Financial costing. 2014. 124 Statutory Declaration I herewith formally declare that I have written the submitted master thesis independently. I did not use any outside support except for the quoted literature and other sources mentioned in the paper. I clearly marked and separately listed all of the literature and all of the other sources which I employed when producing this academic work, either literally or in content. I am aware that the violation of this regulation will lead to failure of the thesis. Haseeb Uz Zaman___________ Student´s name 541108_________________ Matriculation number ________________________ Student´s signature Berlin,15.09.2014_________ Berlin, date