Hektor Cullufi

Premature deterioration of concrete buildings and infrastructure due to corrosion of reinforcement is a severe challenge, both technically and economically. It has been estimated that Western Europe spends 5 billion Euros yearly for repair of corroding concrete infrastructures. Repair-work on the public transportation infrastructure are causing significant inconveniences and delays for both the industry and the general public, and are now recognized as a substantial cost for the society. Set of experiments were conducted in order to produce a description among bars of different types to assist engineers to better comprehend the relative corrosion resistance of those bars. The bars were degreased with solvent, rinsed with de- ionized water and air-dried. After that they were exposed to 5 % NaCl salt spray at 35 o C for up to 3 weeks. The exposure condition followed the ASTM B117 test protocol. During the test the following steps were conducted: Collection rate of salt spray flow was 3 ml/hr; pH adjustment or monitoring was not performed; Visual inspection of the samples was performed after 10, 60, 120, 180, 360 hours and 3 weeks of exposure; During the last three visual inspections, one bar per test condition was removed from the chamber and cleaned following ASTM G1-03 Standard Practice for Preparing, Cleaning, and Evaluating Corrosion Test Specimens methods; The bars were then weighed to obtain weight loss data which was used to calculate average corrosion rates. Stainless steel 316LN and 2205 bars were largely free of corrosion except some minor corrosion product near to cut ends. The coating applied to the cut ends may have generated crevices which are at least partially responsible for the observed corrosion. These two types of stainless bars exhibited phenomenal low corrosion rates, approximately 0.2 % of conventional steel.

The use of fiber reinforced polymer (FRP) bars to substitute the steel bars in internal reinforcement is now an alternative in some structures subjected by corrosion. The strength, stiffness and bond characteristics of FRP bars are tested to understand their flexural behaviour. In this study is investigated the way of failure of beams reinforced internally with carbon FRP (CFRP) bars and their mechanical properties. Two sets of concrete beams reinforced with different diameters of CFRP bars are designed and tested under four-point loading methods. In general, beams reinforced with FRP bars show more deflections and greater values of crack width than beams reinforced with conventional steel, which is due to their low modulus of elasticity and general stiffness. In this paper is presented the calculation and comparison of deflection using different methods, such as ACI 440, CAN/CSA, Eurocode and experimental loading tests. The evaluation is done comparing the results of every method. This study is effective when we use beams with one layer of reinforcement.

Generally, the most important factor of destabilization of natural slopes is the high level of underground water table. It is significant the fact, that many slopes have failed during the winter, after heavy rainfall. Drainage is often a crucial measure due to the important role played by pore-water pressure in reducing shear strength. Because of its high stabilization efficiency in relation to cost, drainage of surface water by superficial ditches, and underground water by networks of trench drains, is one of the most widely used, and generally the most successful stabilization method. The following study is related to a problematic sliding zone in Shijak-Arapaj road.. The landslide in question obtains a specific importance because of its location is closed to the national roadway Tirane-Durres. The landslide has been active for years now. The average presence of a creeping movement of soil masses with a 0.25 m/year velocity. To be able to understand the geological conditions of th...

For seismic design of structures based on European Codes the designers take the peak ground acceleration (PGA) values on ground type A (rock) from the seismic hazard map of Albania. Based on these values and the type of the ground is formed the response spectra which serves as input for seismic analysis of structures. Recent measurements and studies of different authors have emphasized that for the ground classification accepted in EC8 response spectrum values in some cases do not match with reality. So it is necessary, especially when we built on soft soils to do a detailed analysis for propagation and amplification of seismic waves. These analyses are even more important if for the calculation of the structure will be used seismic dynamic analysis in which time history of acceleration is used as input. The paper gives for a real example the wave propagation modelling, the choice of soil parameters, damping coefficients, boundary modelling, finite element size and the integration c...

The use of stainless steel reinforcing bars has recently attracted much attention in the civil engineering community due to its superior material properties, including high corrosion resistance and high specific strength. The use of stainless steel reinforcing bars has recently attracted much attention in the civil engineering community due to its superior material properties, including high corrosion resistance and high specific strength. However, as with all new materials, a number of shortcomings are unavoidable, such as high initial costs, unknown low-cycle fatigue behaviour, and uncertain ductility properties and unidentified bond-slip behaviour between the embedded bar and grouted duct in precast concrete element. MMFX II, is a high strength steel which has recently been introduced on the market was tested, while others were observed for comparison. In this paper we investigate it's low cycle fatigue properties.

Premature deterioration of concrete buildings and infrastructure due to corrosion of reinforcement is a severe challenge, both technically and economically. It has been estimated that Western Europe spends 5 billion Euros yearly for repair of corroding concrete infrastructures. Repair-work on the public transportation infrastructure are causing significant inconveniences and delays for both the industry and the general public, and are now recognized as a substantial cost for the society. Set of experiments were conducted in order to produce a description among bars of different types to assist engineers to better comprehend the relative corrosion resistance of those bars. The bars were degreased with solvent, rinsed with de- ionized water and air-dried. After that they were exposed to 5 % NaCl salt spray at 35 o C for up to 3 weeks. The exposure condition followed the ASTM B117 test protocol. During the test the following steps were conducted: Collection rate of salt spray flow was ...

Nowadays cost of highway materials increase every year. In addition, use of marginal materials results in early development of pavement distress, requiring more frequent repairs also rehabilitation, associated lane closures, traffic congestion in high volume traffic areas which increases the potential for construction zone accidents and increased levels of environmental pollution related to automobile emissions. Therefore, there is a strong desire in our country to optimize the use of materials currently used for highway pavement construction and to seek advanced materials that are cheaper and environmentally friendly. It has now been recognized that the age of limitless construction materials and the use of conventional materials in their present form is fast coming to an end, and new technologies need to be developed to continue to support the rehabilitation and reconstruction of pavements. Today, concerns about limited availability and sustainability are driving the search for ne...

On November 26, 2019 a strong earthquake of magnitude M6.4 occurred close to the City of Durrës, Albania (15.6 km WSW (west southwest) of Mamurras and 22 km SSW (south southwest) of Durrës), causing fatalities and considerable damages in many buildings. In this article we present and analyze, by means of observational data and numerical simulation, the behavior under this earthquake of an 8-floor RC (reinforcement concrete) building, by using design spectra referring to KTP-N.2-89 and Eurocode 8. The main purpose of the authors is to better understand and evaluate the seismic performance of high-rise buildings under the design spectra with a period of soil oscillation close to the fundamental period of the structure.

Concrete has been the most useful material of construction in the recent centuries. It is a mixture, the properties of which change over time. In the residential buildings or infrastructure there have been used various forms of concrete. As a very useful material in the construction, concrete is the element that faces extreme environmental conditions. During the service, the quality of designed concrete can be improved by continuous contact with water as in the case of reservoirs, concrete foundations, etc . But the concrete also can worsen over time due to physical and chemical agents. Consequently, the structures are destroyed when they become unsafe. Degradation of concrete structures has become a crucial matter during the last 20-30 years. Some economically developed countries spend more on repairing and maintenance of structures. As a result, these countries appreciate the longevity of the building rather than the initial cost of its construction. The aim of this paper is to si...

Recently we are using the European Codes for the design of structures for earthquake resistance but in some cases even European Code doesn’t gives realistic results. For irregular structures the European Code gives very simplified recommendations that if will be used for the design gives results that could produce a very heavy and expensive construction. The present paper in the first part will provide information about the EN-Eurocode 8 for Design of Structures for Earthquake Resistance and its limitations. After that will be presented adaptive pushover procedure for nonlinear analysis of irregular structures. The APO theory will be used for the analyses of an existing structure. Firstly in the paper is given the information about the conditions of the existing structure. After that is performed the nonlinear analysis (adaptive pushover) and are given the structural measures suitable for retrofitting this type of structure. In the end, the paper makes recommendations on the methodo...