Khalid Farah - Academia.edu (original) (raw)
Papers by Khalid Farah
This paper presents numerical simulation to the tension behaviour of reinforced concrete (RC) mem... more This paper presents numerical simulation to the tension behaviour of reinforced concrete (RC) members strengthened with externally bonded Carbon Fiber Sheets (CFS) by using two dimensional Rigid Body Spring Model (RBSM) ([1] and [2]). A non-linear reinforced concrete model strengthened by CFS, with bond-slip models and bond deterioration models to simulate both the steel reinforcement bar-concrete interface and the CFS-concrete interface were applied in the RBSM numerical code. It is reported that the RBSM analysis can represent the experimentally observed phenomena very well.
CRC Press eBooks, Oct 21, 2014
This paper presents numerical simulation of the tension behaviour of reinforced concrete (RC) mem... more This paper presents numerical simulation of the tension behaviour of reinforced concrete (RC) members strengthened with externally bonded carbon fiber sheets (CFS) by using two dimensional (2D) rigid body spring model (RBSM). A non-linear RC model strengthened with CFS with bond-slip relations to model the concrete, steel reinforcement interface and concrete, externally bonded CFS interface, and simple models for bond deterioration due to cracking was embedded in the RBSM code that was developed by the authors. Comparison between the RBSM prediction and experimental results shows good agreement. The CFS has shown significant change in the bond stress and average stress of steel reinforcing bar and concrete. In addition the CFS has reduced the crack spacing and gave good crack width control.
This article presents a 3-D modified non-linear elastic model in the strain space. The Helmholtz ... more This article presents a 3-D modified non-linear elastic model in the strain space. The Helmholtz free energy function is introduced with the existence of a dissipation potential surface in the space of thermodynamic conjugate forces. The constitutive equation and the damage evolution were derived as well. The modified damage has been examined to model the nonlinear behavior of reinforced concrete (RC) slabs with an opening. A parametric study with RC was carried out to investigate the impact of different factors on the behavior of RC slabs. These factors are the opening area, the opening shape, the place of opening, and the thickness of the slabs. And the numerical results have been compared with the experimental data from literature. Finally, the model showed its ability to be applied to the structural analysis of RC slabs.
Aswan University Journal of Sciences and Technology
Cold-formed steel (CFS) sections are popular in structural and architectural applications because... more Cold-formed steel (CFS) sections are popular in structural and architectural applications because of their lightweight properties and high strength. To reduce floor height, different types of openings are added to the web of CFS beams, facilitating the passage of building services through the beams. This study aims to investigate the effectiveness of circular web openings in CFS beams using numerical simulations with finite element analysis (FEA) software (ABAQUS). Nonlinear three-dimensional finite element models (FEMs) for two CFS lipped channels were created and validated against experimental test results to determine failure mode and ultimate load-vertical displacement relationships. The models were then used to predict the bending behavior of CFS beams with circular web openings by varying the diameter and location of holes. The results showed that the load capacity of the beams decreased slightly when the ratio of hole diameter to web height (d w /h w) increased up to 0.5. However, there was a more significant decrease in load capacity when (d w /h w) ranged from 0.5 to 0.7.
Life-Cycle of Civil Engineering Systems, 2014
This paper presents numerical simulation of the tension behaviour of reinforced concrete (RC) mem... more This paper presents numerical simulation of the tension behaviour of reinforced concrete (RC) members strengthened with externally bonded carbon fiber sheets (CFS) by using two dimensional (2D) rigid body spring model (RBSM). A non-linear RC model strengthened with CFS with bond-slip relations to model the concrete, steel reinforcement interface and concrete, externally bonded CFS interface, and simple models for bond deterioration due to cracking was embedded in the RBSM code that was developed by the authors. Comparison between the RBSM prediction and experimental results shows good agreement. The CFS has shown significant change in the bond stress and average stress of steel reinforcing bar and concrete. In addition the CFS has reduced the crack spacing and gave good crack width control.
1Msc Candidate, Civil Engineering Dep., Aswan University, Egypt 2Associate Professor, Civil Engin... more 1Msc Candidate, Civil Engineering Dep., Aswan University, Egypt 2Associate Professor, Civil Engineering Dep., Aswan University, Egypt 3Assistant Professor, Civil Engineering Dep., Aswan University, Egypt 4Professor, Civil Engineering Dep., Aswan University, Egypt ----------------------------------------------------------------------***--------------------------------------------------------------------Abstract Due to the superior characteristics of Carbon Fiber Reinforced Polymer (CFRP) especially corrosion resistance, CFRP rods became the suitable replacement of the conventional steel bars. Based on the rigid body spring method (RBSM) a non-linear numerical model was presented to simulate the flexural behavior of beams reinforced with CFRP rods. The presented model supports the nonlinear constitutive laws for the different materials and nonlinear bond stress-slip relationships for FRP rods-concrete and steel rods-concrete interfaces. The degradation of bond between the different re...
1Researcher, Dept. of civil Engineering, Aswan University, Egypt 2Professor, Dept. of civil Engin... more 1Researcher, Dept. of civil Engineering, Aswan University, Egypt 2Professor, Dept. of civil Engineering, Aswan University, Egypt 3Assistant Professor, Dept. of civil Engineering, Aswan University, Egypt ---------------------------------------------------------------------***--------------------------------------------------------------------Abstract In Reinforced Concrete (RC) structural upgrading, there are some instances where opening is needed to be punched through existing (RC) slabs to install new elevators staircases, elevators, escalators, windows and even electrical, heating or ventilation systems. But introducing opening in existing RC slabs can have a severely weaken slabs due to the cut of concrete and reinforcing steel. So, there are various approaches to strengthen RC slabs. These approaches may be requiring a significant usable floor, cumbersome and expensive. This article presents the exerted effort that are taken to understand the structural behavior of RC slabs with...
The reduction in dapped end beams depth nearby the supports tends to produce stress concentration... more The reduction in dapped end beams depth nearby the supports tends to produce stress concentration and hence results in shear cracks, if it does not have an adequate reinforcement detailing. This study investigates numerically the efficiency of applying different external strengthening techniques to the dapped end of such beams. A two-dimensional finite element model was built to predict the structural behavior of dapped ends strengthened with different techniques. The techniques included external bonding of the steel angle at the re-entrant corner, un-bounded bolt anchoring, external steel plate jacketing, exterior carbon fiber wrapping and/or stripping and external inclined steel plates. The FE analysis results are then presented in terms of the ultimate load capacities, load-deflection and crack pattern at failure. The results showed that the FE model, at various stages, was found to be comparable to the available test data. Moreover, it enabled the capture of the failure progress...
This paper presents numerical simulation to the tension behaviour of reinforced concrete (RC) mem... more This paper presents numerical simulation to the tension behaviour of reinforced concrete (RC) members strengthened with externally bonded Carbon Fiber Sheets (CFS) by using two dimensional Rigid Body Spring Model (RBSM) ([1] and [2]). A non-linear reinforced concrete model strengthened by CFS, with bond-slip models and bond deterioration models to simulate both the steel reinforcement bar–concrete interface and the CFS-concrete interface were applied in the RBSM numerical code. It is reported that the RBSM analysis can represent the experimentally observed phenomena very well.
This paper presents numerical simulation to the tension behaviour of reinforced concrete (RC) mem... more This paper presents numerical simulation to the tension behaviour of reinforced concrete (RC) members strengthened with externally bonded Carbon Fiber Sheets (CFS) by using two dimensional Rigid Body Spring Model (RBSM) ([1] and [2]). A non-linear reinforced concrete model strengthened by CFS, with bond-slip models and bond deterioration models to simulate both the steel reinforcement bar-concrete interface and the CFS-concrete interface were applied in the RBSM numerical code. It is reported that the RBSM analysis can represent the experimentally observed phenomena very well.
CRC Press eBooks, Oct 21, 2014
This paper presents numerical simulation of the tension behaviour of reinforced concrete (RC) mem... more This paper presents numerical simulation of the tension behaviour of reinforced concrete (RC) members strengthened with externally bonded carbon fiber sheets (CFS) by using two dimensional (2D) rigid body spring model (RBSM). A non-linear RC model strengthened with CFS with bond-slip relations to model the concrete, steel reinforcement interface and concrete, externally bonded CFS interface, and simple models for bond deterioration due to cracking was embedded in the RBSM code that was developed by the authors. Comparison between the RBSM prediction and experimental results shows good agreement. The CFS has shown significant change in the bond stress and average stress of steel reinforcing bar and concrete. In addition the CFS has reduced the crack spacing and gave good crack width control.
This article presents a 3-D modified non-linear elastic model in the strain space. The Helmholtz ... more This article presents a 3-D modified non-linear elastic model in the strain space. The Helmholtz free energy function is introduced with the existence of a dissipation potential surface in the space of thermodynamic conjugate forces. The constitutive equation and the damage evolution were derived as well. The modified damage has been examined to model the nonlinear behavior of reinforced concrete (RC) slabs with an opening. A parametric study with RC was carried out to investigate the impact of different factors on the behavior of RC slabs. These factors are the opening area, the opening shape, the place of opening, and the thickness of the slabs. And the numerical results have been compared with the experimental data from literature. Finally, the model showed its ability to be applied to the structural analysis of RC slabs.
Aswan University Journal of Sciences and Technology
Cold-formed steel (CFS) sections are popular in structural and architectural applications because... more Cold-formed steel (CFS) sections are popular in structural and architectural applications because of their lightweight properties and high strength. To reduce floor height, different types of openings are added to the web of CFS beams, facilitating the passage of building services through the beams. This study aims to investigate the effectiveness of circular web openings in CFS beams using numerical simulations with finite element analysis (FEA) software (ABAQUS). Nonlinear three-dimensional finite element models (FEMs) for two CFS lipped channels were created and validated against experimental test results to determine failure mode and ultimate load-vertical displacement relationships. The models were then used to predict the bending behavior of CFS beams with circular web openings by varying the diameter and location of holes. The results showed that the load capacity of the beams decreased slightly when the ratio of hole diameter to web height (d w /h w) increased up to 0.5. However, there was a more significant decrease in load capacity when (d w /h w) ranged from 0.5 to 0.7.
Life-Cycle of Civil Engineering Systems, 2014
This paper presents numerical simulation of the tension behaviour of reinforced concrete (RC) mem... more This paper presents numerical simulation of the tension behaviour of reinforced concrete (RC) members strengthened with externally bonded carbon fiber sheets (CFS) by using two dimensional (2D) rigid body spring model (RBSM). A non-linear RC model strengthened with CFS with bond-slip relations to model the concrete, steel reinforcement interface and concrete, externally bonded CFS interface, and simple models for bond deterioration due to cracking was embedded in the RBSM code that was developed by the authors. Comparison between the RBSM prediction and experimental results shows good agreement. The CFS has shown significant change in the bond stress and average stress of steel reinforcing bar and concrete. In addition the CFS has reduced the crack spacing and gave good crack width control.
1Msc Candidate, Civil Engineering Dep., Aswan University, Egypt 2Associate Professor, Civil Engin... more 1Msc Candidate, Civil Engineering Dep., Aswan University, Egypt 2Associate Professor, Civil Engineering Dep., Aswan University, Egypt 3Assistant Professor, Civil Engineering Dep., Aswan University, Egypt 4Professor, Civil Engineering Dep., Aswan University, Egypt ----------------------------------------------------------------------***--------------------------------------------------------------------Abstract Due to the superior characteristics of Carbon Fiber Reinforced Polymer (CFRP) especially corrosion resistance, CFRP rods became the suitable replacement of the conventional steel bars. Based on the rigid body spring method (RBSM) a non-linear numerical model was presented to simulate the flexural behavior of beams reinforced with CFRP rods. The presented model supports the nonlinear constitutive laws for the different materials and nonlinear bond stress-slip relationships for FRP rods-concrete and steel rods-concrete interfaces. The degradation of bond between the different re...
1Researcher, Dept. of civil Engineering, Aswan University, Egypt 2Professor, Dept. of civil Engin... more 1Researcher, Dept. of civil Engineering, Aswan University, Egypt 2Professor, Dept. of civil Engineering, Aswan University, Egypt 3Assistant Professor, Dept. of civil Engineering, Aswan University, Egypt ---------------------------------------------------------------------***--------------------------------------------------------------------Abstract In Reinforced Concrete (RC) structural upgrading, there are some instances where opening is needed to be punched through existing (RC) slabs to install new elevators staircases, elevators, escalators, windows and even electrical, heating or ventilation systems. But introducing opening in existing RC slabs can have a severely weaken slabs due to the cut of concrete and reinforcing steel. So, there are various approaches to strengthen RC slabs. These approaches may be requiring a significant usable floor, cumbersome and expensive. This article presents the exerted effort that are taken to understand the structural behavior of RC slabs with...
The reduction in dapped end beams depth nearby the supports tends to produce stress concentration... more The reduction in dapped end beams depth nearby the supports tends to produce stress concentration and hence results in shear cracks, if it does not have an adequate reinforcement detailing. This study investigates numerically the efficiency of applying different external strengthening techniques to the dapped end of such beams. A two-dimensional finite element model was built to predict the structural behavior of dapped ends strengthened with different techniques. The techniques included external bonding of the steel angle at the re-entrant corner, un-bounded bolt anchoring, external steel plate jacketing, exterior carbon fiber wrapping and/or stripping and external inclined steel plates. The FE analysis results are then presented in terms of the ultimate load capacities, load-deflection and crack pattern at failure. The results showed that the FE model, at various stages, was found to be comparable to the available test data. Moreover, it enabled the capture of the failure progress...
This paper presents numerical simulation to the tension behaviour of reinforced concrete (RC) mem... more This paper presents numerical simulation to the tension behaviour of reinforced concrete (RC) members strengthened with externally bonded Carbon Fiber Sheets (CFS) by using two dimensional Rigid Body Spring Model (RBSM) ([1] and [2]). A non-linear reinforced concrete model strengthened by CFS, with bond-slip models and bond deterioration models to simulate both the steel reinforcement bar–concrete interface and the CFS-concrete interface were applied in the RBSM numerical code. It is reported that the RBSM analysis can represent the experimentally observed phenomena very well.