Professor of concrete structures, Ain Shams University, Cairo, Egypt. Was working as professor of Structure Engineering at UAE University for 10 years. Managing Director of eFORCE Engineering, Dubai. Graduated from McMaster University, Canada.
... is to develop a ductile system that allows energy dissipation at the plastic hinge zones. ...... more ... is to develop a ductile system that allows energy dissipation at the plastic hinge zones. ... reinforced concrete buildings were selected for the purpose of the analysis of the effect of joint ... the UBC-64 [11], the load combination that included wind load and gravity loads controlled the ...
Arabian journal for science and engineering, Jan 25, 2012
Environmental conditions in the Gulf region are considered to be very aggressive to most structur... more Environmental conditions in the Gulf region are considered to be very aggressive to most structures. The main objective of the paper is to study the performance of RC elements (beams and slabs) strengthened by externally bonded FRP using carbon fiber-reinforced polymer (CFRP) sheets and strips and exposed to different environmental conditions. Six exposure conditions were used in the investigation to represent the Gulf region various environments. The exposure conditions used are laboratory, site, high temperature and humidity, cyclic drinking water, cyclic sea water and being embedded in Sabkha soil. The results presented in this paper are a part of a 36-month study program to evaluate the performance of different strengthened RC elements. This paper includes the 18-month test results after exposing the specimens to different environmental conditions. Comparison of the test results with the virgin elements (i.e. at 28 days of age and not exposed to the different environments) is carried out to quantify the change in performance of the elements. The performance of the structural elements is evaluated by measuring various deformations such as deflections, concrete strain, reinforcing steel strain and strain in the CFRP sheets and strips. Also, the mode of failure is reported. It was found that beams and slabs strengthened with CFRP strips were greatly affected by the exposure conditions compared with those strengthened by CFRP sheets. Sabkha soil and sea water were found to be the most aggressive environments.
... a United Arab Emirates University, Mechanical Engineering Department, Al-Ain, United Arab Emi... more ... a United Arab Emirates University, Mechanical Engineering Department, Al-Ain, United Arab Emirates. ... These systems are to be used in strengthening the concrete structure in Abu Dhabi Company for Onshore Oil Operations (ADCO), hence the most durable system was ...
As building codes are updated, some of the existing important structures may fall short of comply... more As building codes are updated, some of the existing important structures may fall short of complying with current standards even though they may have been properly designed and constructed according to earlier codes. Many existing structures may be inadequate and may pose severe risk during seismic events. Rehabilitation measures to upgrade the capacity of these structures can be performed at some point in their useful lives especially when located in seismically active zones. A new method for improving the seismic performance of existing reinforced concrete structures is by jacketing the deficient connections using corrugated steel jackets. An experimental program was conducted to evaluate this method of rehabilitation. Corrugated steel jacketing addresses the particular weakness that is often found in existing reinforced concrete structures, namely the lack of sufficient shear reinforcement and the required confining reinforcement within the joints and in adjoining beams and columns. The performance of four reinforced concrete connections was determined experimentally. The test specimens include one connection representing existing structures, one designed according to current seismic codes and two rehabilitated connections. The test results showed satisfactory performance at high cyclic load levels and significant increase in the shear capacity and ductility of connections rehabilitated with corrugated steel jackets.
Fiber-reinforced plastic (FRP) products are being currently used in construction. Compared with s... more Fiber-reinforced plastic (FRP) products are being currently used in construction. Compared with steel, FRP products have the following advantages: non-corrosive, non-magnetic, high ratio of strength to weight, high durability, inherent resistance to weather and the corrosive effect of caustics and salts as well as aggressive chemicals. However, in case of structural applications, deflection control is usually expected to be the limiting factor in design rather than strength control. The objective of this research project is to investigate design options for a composite concrete slab without the use of ferrous materials but with relatively high stiffness. This is to avoid the current problem of deterioration of concrete due to expansion because of rusting reinforcement members. Such a target can be achieved by replacing the steel reinforcement of concrete slabs with pultruded I-shape glass FRP (GFRP) structural sections (pultruded GFRP grating sections). The composite action between the FRP structural shapes and the concrete aims to reduce the previous observed high deformation when FRP rebars were used in the concrete. An experimental investigation was conducted to study the applicability and behaviour of pultruded GFRP grating as a reinforcement of one-way concrete slabs and compare its behaviour with that of concrete slab reinforced by either steel or FRP rebars. Nine medium-scale specimens were cast and tested under flexural loading. The first two specimens were used as control concrete slabs reinforced using different amount of reinforcing steel rebars. The third and fourth specimens were concrete slab reinforced using different amount of FRP rebars. The fifth specimen was a pultruded fiberglass grating without concrete. The sixth, seventh, eighth and ninth specimens were concrete slabs reinforced using pultruded fiberglass grating instead of steel reinforcement with different slab thickness. The experimental ultimate capacity of each of the tested slab was compared to the predicted theoretical capacity using compatibility of strains and equilibrium of forces. The comparison showed that the predicted theoretical values were in good agreement with the experimental ones. The test results indicated the feasibility of using pultruded fiberglass grating in resisting bending and shear stresses with reasonable ductility. This research clarified the behaviour of the composite action of pultruded fiberglass grating with concrete slabs showing it to be an alternative successful construction system. Useful Information for the designers, researchers are provided in the field of composite action of reinforced concrete slabs.
The use of Fiber Reinforced Polymer (FRP) Composites is one of the latest significant development... more The use of Fiber Reinforced Polymer (FRP) Composites is one of the latest significant developments in the field of bridge construction. FRP composites have been the material of choice in the aerospace industry since 1960s. However, only recently glass FRP composites have been gaining both popularity and acceptance as one of the structural materials of choice because of their high strength and stiffness to weight ratio, and corrosion resistance. This paper demonstrates the possibility of combining composite materials with a low-cost construction material (i.e. concrete) resulting in a new concept of designing lightweight, corrosion immune, yet inexpensive beams having acceptable structural properties. Pultruded FRP beam section-to-concrete slab is proposed to behave under bending as a composite beam. The objectives of the proposed research are to investigate the composite behaviour of FRP members with reinforced concrete slabs and comparing the behaviour of fully encased FRP beams with that of FRP beams mechanically anchored to the concrete. An experimental program was conducted to demonstrate the behaviour of the pultruded FRP beam-toconcrete slab in composite action. Three large scale specimens of 2.25 m length were tested under four-point loading. The first specimen is a pultruded FRP beam used as a control beam. The second specimen consists of pultruded FRP beam-to-concrete slab acting as a composite beam. The third specimen is a fully concrete encased FRP beam. The test results indicated the feasibility of using hybrid FRP-concrete beam to increase the load carrying capacity in flexure as well as beam stiffness. The outcome of this research provides substantial information for both designers and researchers in the field of FRP composites.
ABSTRACT A macro-element model is developed to account for shear deformation and bond slip of rei... more ABSTRACT A macro-element model is developed to account for shear deformation and bond slip of reinforcement bars in the beam-column joint region of reinforced concrete structures. The joint region is idealized by two springs in series, one representing shear deformation and the other representing bond slip. The softened truss model theory is adopted to establish the shear force-shear deformation relationship and to determine the shear capacity of the joint. A detailed model for the bond slip of the reinforcing bars at the beam-column interface is presented. The proposed macro-element model of the joint is validated using available experimental data on beam-column connections representing exterior joints in ductile and nonductile frames.
Earthquake Engineering and Structural Dynamics, 1999
.The structure’s ability to survive an earthquake may be measured in terms of the expected state ... more .The structure’s ability to survive an earthquake may be measured in terms of the expected state of damage of the structure after the earthquake. Damage may be quantified by using any of several damage indices defined as functions whose values can be related to particular structural damage states. A number of available response-based damage indices are discussed and critically evaluated for their applicability in seismic damage evaluation. A new rational approach for damage assessment is presented which provides a measure of the physical response characteristics of the structure and is better suited for non-linear structural analysis. A practical method based on the static pushover analysis is proposed to estimate the expected damage to structures when subjected to earthquakes of different intensities. Results of the analysis of ductile and non-ductile reinforced concrete buildings show that the proposed procedure for damage assessment gives a simple, consistent and rational damage indicator for structures.
The rehabilitation of existing buildings requires an assessment of their lateral load resisting c... more The rehabilitation of existing buildings requires an assessment of their lateral load resisting capacity which may be limited by the strength and ductility capacity of their critical regions. From this assessment, a rehabilitation strategy can be formulated. Lack of adequate confinement and shear reinforcement in the beam-column joints of existing reinforced concrete frames may be the cause of brittle failure during a seismic event. Most of the nonlinear dynamic analysis programs assume infinitely rigid beamcolumn joints in concrete frames regardless of the reinforcement detail. To properly analyze existing structures, a joint element is proposed and introduced in the nonlinear dynamic analysis. The developed joint element accounts for inelastic shear deformation and bar bond slip. The response of three-and nine-story existing frames with joint elements when subjected to dynamic loading was compared with the response of frames with rigid joint assumption and the response of rehabilitated frames. The results show that the modelling of inelastic shear deformation in joints has a significant effect on the seismic response in terms of drift and damage. The rigid joint assumption was found to be inappropriate when assessing the behaviour of existing nonductile structures.
... a United Arab Emirates University, Mechanical Engineering Department, Al-Ain, United Arab Emi... more ... a United Arab Emirates University, Mechanical Engineering Department, Al-Ain, United Arab Emirates. ... These systems are to be used in strengthening the concrete structure in Abu Dhabi Company for Onshore Oil Operations (ADCO), hence the most durable system was ...
An experimental investigation was conducted to study the failure mode of existing reinforcod conc... more An experimental investigation was conducted to study the failure mode of existing reinforcod concrete columns designed during the 1960s. The effectiveness of using corrugated steel jackets for enhancing the seismic flexural strength and ductility of these types of columns was examined. Three large-scale columns were tested under cyclic loading. T h e three columns represent existing column, current codedetailed column and rehabilitated coSurnn. The variables in the test specimens include the amount of column transverse r e inforcement and jafketing of the column. The corrugated jacket was found to be effective in the rehabilitation of the selected existing structure, wbich does not meet the current seismic code requirements. A method is p r o p d for the design of the corrugated steel jacket to enhance the lap splice capacity and ductility of the column.
The main purpose of this paper is to present an experimental campaign of different strategies for... more The main purpose of this paper is to present an experimental campaign of different strategies for the seismic retrofit of RC columns, comparing the obtained results with analytical methodologies, and evaluating benefits concerning their structural behaviour under the ...
Procedures and computer programs are developed for determining the response of soil-foundation-st... more Procedures and computer programs are developed for determining the response of soil-foundation-structure interaction systems during earthquakes and to investigate the nature of soil and interaction effects. Assuming the linear elastic stress-strain behavior of the soil, the author develops a two-dimensional analytical model of soil-foundation-structure interaction. The model consists of one-dimensional structural members, a two-dimensional rigid foundation block, and quadrilateral finite elements which idealize soil deposits. The ...
ACI is a technical and educational society dedicated to improving the design, construction, maint... more ACI is a technical and educational society dedicated to improving the design, construction, maintenance and repair of concrete structures.
... 3 hours lecture A study of the theory and practice of plane surveying as applied to property ... more ... 3 hours lecture A study of the theory and practice of plane surveying as applied to property ... 4 CIS 360 Algorithms & Data Structures 3 CIS 361 Models of Computation 3 CIS ... syntax and semantics of a high level programming language, debugging and verification of programs. ...
... is to develop a ductile system that allows energy dissipation at the plastic hinge zones. ...... more ... is to develop a ductile system that allows energy dissipation at the plastic hinge zones. ... reinforced concrete buildings were selected for the purpose of the analysis of the effect of joint ... the UBC-64 [11], the load combination that included wind load and gravity loads controlled the ...
Arabian journal for science and engineering, Jan 25, 2012
Environmental conditions in the Gulf region are considered to be very aggressive to most structur... more Environmental conditions in the Gulf region are considered to be very aggressive to most structures. The main objective of the paper is to study the performance of RC elements (beams and slabs) strengthened by externally bonded FRP using carbon fiber-reinforced polymer (CFRP) sheets and strips and exposed to different environmental conditions. Six exposure conditions were used in the investigation to represent the Gulf region various environments. The exposure conditions used are laboratory, site, high temperature and humidity, cyclic drinking water, cyclic sea water and being embedded in Sabkha soil. The results presented in this paper are a part of a 36-month study program to evaluate the performance of different strengthened RC elements. This paper includes the 18-month test results after exposing the specimens to different environmental conditions. Comparison of the test results with the virgin elements (i.e. at 28 days of age and not exposed to the different environments) is carried out to quantify the change in performance of the elements. The performance of the structural elements is evaluated by measuring various deformations such as deflections, concrete strain, reinforcing steel strain and strain in the CFRP sheets and strips. Also, the mode of failure is reported. It was found that beams and slabs strengthened with CFRP strips were greatly affected by the exposure conditions compared with those strengthened by CFRP sheets. Sabkha soil and sea water were found to be the most aggressive environments.
... a United Arab Emirates University, Mechanical Engineering Department, Al-Ain, United Arab Emi... more ... a United Arab Emirates University, Mechanical Engineering Department, Al-Ain, United Arab Emirates. ... These systems are to be used in strengthening the concrete structure in Abu Dhabi Company for Onshore Oil Operations (ADCO), hence the most durable system was ...
As building codes are updated, some of the existing important structures may fall short of comply... more As building codes are updated, some of the existing important structures may fall short of complying with current standards even though they may have been properly designed and constructed according to earlier codes. Many existing structures may be inadequate and may pose severe risk during seismic events. Rehabilitation measures to upgrade the capacity of these structures can be performed at some point in their useful lives especially when located in seismically active zones. A new method for improving the seismic performance of existing reinforced concrete structures is by jacketing the deficient connections using corrugated steel jackets. An experimental program was conducted to evaluate this method of rehabilitation. Corrugated steel jacketing addresses the particular weakness that is often found in existing reinforced concrete structures, namely the lack of sufficient shear reinforcement and the required confining reinforcement within the joints and in adjoining beams and columns. The performance of four reinforced concrete connections was determined experimentally. The test specimens include one connection representing existing structures, one designed according to current seismic codes and two rehabilitated connections. The test results showed satisfactory performance at high cyclic load levels and significant increase in the shear capacity and ductility of connections rehabilitated with corrugated steel jackets.
Fiber-reinforced plastic (FRP) products are being currently used in construction. Compared with s... more Fiber-reinforced plastic (FRP) products are being currently used in construction. Compared with steel, FRP products have the following advantages: non-corrosive, non-magnetic, high ratio of strength to weight, high durability, inherent resistance to weather and the corrosive effect of caustics and salts as well as aggressive chemicals. However, in case of structural applications, deflection control is usually expected to be the limiting factor in design rather than strength control. The objective of this research project is to investigate design options for a composite concrete slab without the use of ferrous materials but with relatively high stiffness. This is to avoid the current problem of deterioration of concrete due to expansion because of rusting reinforcement members. Such a target can be achieved by replacing the steel reinforcement of concrete slabs with pultruded I-shape glass FRP (GFRP) structural sections (pultruded GFRP grating sections). The composite action between the FRP structural shapes and the concrete aims to reduce the previous observed high deformation when FRP rebars were used in the concrete. An experimental investigation was conducted to study the applicability and behaviour of pultruded GFRP grating as a reinforcement of one-way concrete slabs and compare its behaviour with that of concrete slab reinforced by either steel or FRP rebars. Nine medium-scale specimens were cast and tested under flexural loading. The first two specimens were used as control concrete slabs reinforced using different amount of reinforcing steel rebars. The third and fourth specimens were concrete slab reinforced using different amount of FRP rebars. The fifth specimen was a pultruded fiberglass grating without concrete. The sixth, seventh, eighth and ninth specimens were concrete slabs reinforced using pultruded fiberglass grating instead of steel reinforcement with different slab thickness. The experimental ultimate capacity of each of the tested slab was compared to the predicted theoretical capacity using compatibility of strains and equilibrium of forces. The comparison showed that the predicted theoretical values were in good agreement with the experimental ones. The test results indicated the feasibility of using pultruded fiberglass grating in resisting bending and shear stresses with reasonable ductility. This research clarified the behaviour of the composite action of pultruded fiberglass grating with concrete slabs showing it to be an alternative successful construction system. Useful Information for the designers, researchers are provided in the field of composite action of reinforced concrete slabs.
The use of Fiber Reinforced Polymer (FRP) Composites is one of the latest significant development... more The use of Fiber Reinforced Polymer (FRP) Composites is one of the latest significant developments in the field of bridge construction. FRP composites have been the material of choice in the aerospace industry since 1960s. However, only recently glass FRP composites have been gaining both popularity and acceptance as one of the structural materials of choice because of their high strength and stiffness to weight ratio, and corrosion resistance. This paper demonstrates the possibility of combining composite materials with a low-cost construction material (i.e. concrete) resulting in a new concept of designing lightweight, corrosion immune, yet inexpensive beams having acceptable structural properties. Pultruded FRP beam section-to-concrete slab is proposed to behave under bending as a composite beam. The objectives of the proposed research are to investigate the composite behaviour of FRP members with reinforced concrete slabs and comparing the behaviour of fully encased FRP beams with that of FRP beams mechanically anchored to the concrete. An experimental program was conducted to demonstrate the behaviour of the pultruded FRP beam-toconcrete slab in composite action. Three large scale specimens of 2.25 m length were tested under four-point loading. The first specimen is a pultruded FRP beam used as a control beam. The second specimen consists of pultruded FRP beam-to-concrete slab acting as a composite beam. The third specimen is a fully concrete encased FRP beam. The test results indicated the feasibility of using hybrid FRP-concrete beam to increase the load carrying capacity in flexure as well as beam stiffness. The outcome of this research provides substantial information for both designers and researchers in the field of FRP composites.
ABSTRACT A macro-element model is developed to account for shear deformation and bond slip of rei... more ABSTRACT A macro-element model is developed to account for shear deformation and bond slip of reinforcement bars in the beam-column joint region of reinforced concrete structures. The joint region is idealized by two springs in series, one representing shear deformation and the other representing bond slip. The softened truss model theory is adopted to establish the shear force-shear deformation relationship and to determine the shear capacity of the joint. A detailed model for the bond slip of the reinforcing bars at the beam-column interface is presented. The proposed macro-element model of the joint is validated using available experimental data on beam-column connections representing exterior joints in ductile and nonductile frames.
Earthquake Engineering and Structural Dynamics, 1999
.The structure’s ability to survive an earthquake may be measured in terms of the expected state ... more .The structure’s ability to survive an earthquake may be measured in terms of the expected state of damage of the structure after the earthquake. Damage may be quantified by using any of several damage indices defined as functions whose values can be related to particular structural damage states. A number of available response-based damage indices are discussed and critically evaluated for their applicability in seismic damage evaluation. A new rational approach for damage assessment is presented which provides a measure of the physical response characteristics of the structure and is better suited for non-linear structural analysis. A practical method based on the static pushover analysis is proposed to estimate the expected damage to structures when subjected to earthquakes of different intensities. Results of the analysis of ductile and non-ductile reinforced concrete buildings show that the proposed procedure for damage assessment gives a simple, consistent and rational damage indicator for structures.
The rehabilitation of existing buildings requires an assessment of their lateral load resisting c... more The rehabilitation of existing buildings requires an assessment of their lateral load resisting capacity which may be limited by the strength and ductility capacity of their critical regions. From this assessment, a rehabilitation strategy can be formulated. Lack of adequate confinement and shear reinforcement in the beam-column joints of existing reinforced concrete frames may be the cause of brittle failure during a seismic event. Most of the nonlinear dynamic analysis programs assume infinitely rigid beamcolumn joints in concrete frames regardless of the reinforcement detail. To properly analyze existing structures, a joint element is proposed and introduced in the nonlinear dynamic analysis. The developed joint element accounts for inelastic shear deformation and bar bond slip. The response of three-and nine-story existing frames with joint elements when subjected to dynamic loading was compared with the response of frames with rigid joint assumption and the response of rehabilitated frames. The results show that the modelling of inelastic shear deformation in joints has a significant effect on the seismic response in terms of drift and damage. The rigid joint assumption was found to be inappropriate when assessing the behaviour of existing nonductile structures.
... a United Arab Emirates University, Mechanical Engineering Department, Al-Ain, United Arab Emi... more ... a United Arab Emirates University, Mechanical Engineering Department, Al-Ain, United Arab Emirates. ... These systems are to be used in strengthening the concrete structure in Abu Dhabi Company for Onshore Oil Operations (ADCO), hence the most durable system was ...
An experimental investigation was conducted to study the failure mode of existing reinforcod conc... more An experimental investigation was conducted to study the failure mode of existing reinforcod concrete columns designed during the 1960s. The effectiveness of using corrugated steel jackets for enhancing the seismic flexural strength and ductility of these types of columns was examined. Three large-scale columns were tested under cyclic loading. T h e three columns represent existing column, current codedetailed column and rehabilitated coSurnn. The variables in the test specimens include the amount of column transverse r e inforcement and jafketing of the column. The corrugated jacket was found to be effective in the rehabilitation of the selected existing structure, wbich does not meet the current seismic code requirements. A method is p r o p d for the design of the corrugated steel jacket to enhance the lap splice capacity and ductility of the column.
The main purpose of this paper is to present an experimental campaign of different strategies for... more The main purpose of this paper is to present an experimental campaign of different strategies for the seismic retrofit of RC columns, comparing the obtained results with analytical methodologies, and evaluating benefits concerning their structural behaviour under the ...
Procedures and computer programs are developed for determining the response of soil-foundation-st... more Procedures and computer programs are developed for determining the response of soil-foundation-structure interaction systems during earthquakes and to investigate the nature of soil and interaction effects. Assuming the linear elastic stress-strain behavior of the soil, the author develops a two-dimensional analytical model of soil-foundation-structure interaction. The model consists of one-dimensional structural members, a two-dimensional rigid foundation block, and quadrilateral finite elements which idealize soil deposits. The ...
ACI is a technical and educational society dedicated to improving the design, construction, maint... more ACI is a technical and educational society dedicated to improving the design, construction, maintenance and repair of concrete structures.
... 3 hours lecture A study of the theory and practice of plane surveying as applied to property ... more ... 3 hours lecture A study of the theory and practice of plane surveying as applied to property ... 4 CIS 360 Algorithms & Data Structures 3 CIS 361 Models of Computation 3 CIS ... syntax and semantics of a high level programming language, debugging and verification of programs. ...
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Papers by Ashraf Biddah