Degradation in reinforced concrete (RC) members associated with rebar corrosion in old buildings ... more Degradation in reinforced concrete (RC) members associated with rebar corrosion in old buildings is one major concern that can significantly affect the strength and serviceability of RC structures. Strengthening existing structures using FRP can comprise complex assessment and design processes. This study addresses the critical issue of modeling the behavior associated with steel reinforcement corrosion in RC slab-column joints (SCJs). Three modeling methods, namely artificial neural network (ANN), Eureqa’s symbolic regression algorithm, and analytical modeling, are proposed to predict the punching shear (PS) capacity of corroded RC SCJs by accounting for the changes in material properties due to corrosion and the strengthening provided by different types of FRP. The accuracy of the proposed models is validated through comparisons with experimental results and a verified finite element (FE) model that considers material deterioration and bond degradation. The results demonstrate that the proposed models offer more accurate PS capacity predictions than existing design codes. Among the considered prediction models, the ANN model exhibits superior performance and is recommended for PS capacity prediction. A practical design tool in the form of a graphical user interface (GUI) was created to facilitate the assessment and prediction of the PS behavior of corroded RC SCJs. Engineers can conveniently use this GUI to evaluate and predict the performance of such joints.
International Journal of Civil and Structural Engineering, 2011
In this paper, the results of an analytical investigation on the behavior of RC columns reinforce... more In this paper, the results of an analytical investigation on the behavior of RC columns reinforced with fiber reinforced polymer bars FRP are presented and discussed. Nonlinear finite element analysis on 10column specimens was achieved by using ANSYS software. The nonlinear finite element analysis program ANSYS is utilised owing to its capabilities to predict either the response of reinforced concrete columns in the postelastic range or the ultimate strength of a reinforced concrete columns reinforced by FRP bars. An extensive set of parameters is investigated including different main reinforcement ratios, main reinforcement types (GFRP, Steel), the transverse reinforcement ratios, and the characteristic compressive strength of concrete. A comparison between the experimental results and those predicted by the existing models are presented. Results and conclusions may be useful for designers, have been raised, and represented.
This paper studied the reinforced concrete (RC) slender columns with rectangular sections behavio... more This paper studied the reinforced concrete (RC) slender columns with rectangular sections behavior when strengthened by carbon fiber reinforced polymers (CFRPs) and exposed to eccentric loads. Nine specimens with a rectangular slender cross-section (210x150mm) were tested with lengths of 3000mm (λ= 70), 2500mm (λ= 58), and 2000mm (λ= 46). Samples were fabricated as slender columns using two strategies. The first strategy is CFRP strengthening with near-surface mounted longitudinally (L-NSM) CFRP strips. The second strategy is composed of a new method where longitudinal near surface mounted (L-NSM) CFRP strips is retrofitted with transverse CFRP sheet wrapping. And the results were used to explore the impact of CFRP retrofitting techniques on the columns. A numerical investigation was performed to examine further key variables' effects on RC columns, demonstrating acceptable outcome with the experimental findings. For all tests, specimens were loaded under compressive axial static. The compression force was applied at an initial eccentricity of 35 mm. Moreover, based on the experimental results of the current investigation, the validated models were used in a comprehensive parametric study comprising fifteen new analytical models to check the effects of key variables expected to impact the behavior of NSM and CFRP-confined RC columns. The key conclusions the study provided are that CFRP retrofitting techniques can enhance axial and flexural rigidity and improve the RC columns performance. Additionally, the study revealed that different retrofitting techniques had different impacts on the RC columns behavior, depending on the slender.
International Journal of Advanced Structural Engineering, Dec 1, 2011
In this paper, the results of an analytical investigation on the behavior of RC columns reinforce... more In this paper, the results of an analytical investigation on the behavior of RC columns reinforced with fiber reinforced polymer bars FRP are presented and discussed. Nonlinear finite element analysis on 10column specimens was achieved by using ANSYS software. The nonlinear finite element analysis program ANSYS is utilised owing to its capabilities to predict either the response of reinforced concrete columns in the postelastic range or the ultimate strength of a reinforced concrete columns reinforced by FRP bars. An extensive set of parameters is investigated including different main reinforcement ratios, main reinforcement types (GFRP, Steel), the transverse reinforcement ratios, and the characteristic compressive strength of concrete. A comparison between the experimental results and those predicted by the existing models are presented. Results and conclusions may be useful for designers, have been raised, and represented.
The behavior of reinforced concrete columns with holes under axial load is not understood, and re... more The behavior of reinforced concrete columns with holes under axial load is not understood, and researches in the subject are needed to help designers and structural code officials. Holes drilled out to install additional services or equipment, such as for ducts through columns, beams, or walls, can lead to loss of strength and possible structural failure. Until now little work has been done on holes in columns and, hence, this study aims to examine the amount of strength lost due to the presence of holes in columns. Nonlinear finite element analysis on 21-column specimens was achieved by using ANSYS software. The nonlinear finite element analysis program ANSYS is utilized owing to its capabilities to predict either the response of reinforced concrete columns in the post-elastic range or the ultimate strength of reinforced concrete columns. An extensive set of parameters is investigated including different parameters; dimensions of the holes with diameter 0.1, 0.15, 0.2 and 0.3 of column length, their relative position in columns, and the shape of holes; circle and square. A comparison between the experimental results and those predicted by the existing models are presented. Results and conclusions may be useful for designers, have been raised, and represented. Keyword: Inelastic finite element analysis, columns, holes, strength and testing of materials.
In this paper, the results of an analytical investigation on the behavior of RC columns reinforce... more In this paper, the results of an analytical investigation on the behavior of RC columns reinforced with fiber reinforced polymer bars FRP are presented and discussed. Nonlinear finite element analysis on 10column specimens was achieved by using ANSYS software. The nonlinear finite element analysis program ANSYS is utilised owing to its capabilities to predict either the response of reinforced concrete columns in the postelastic range or the ultimate strength of a reinforced concrete columns reinforced by FRP bars. An extensive set of parameters is investigated including different main reinforcement ratios, main reinforcement types (GFRP, Steel), the transverse reinforcement ratios, and the characteristic compressive strength of concrete. A comparison between the experimental results and those predicted by the existing models are presented. Results and conclusions may be useful for designers, have been raised, and represented.
Strengthening of existing Reinforced Concrete structures is becoming a major issue in civil engin... more Strengthening of existing Reinforced Concrete structures is becoming a major issue in civil engineering. Externally Bonded Reinforcement (EBR) systems have been successfully applied for strengthening of existing concrete structures. This work includes a results of numerical models carried to investigate the behavior of reinforced concrete, RC, slender columns with rectangular sections under the effect of eccentric loads strengthened with carbon fiber-reinforced polymers (CFRPs) in three different manners in order to enhance its axial and flexural rigidity. The first approach is a well-known form of CFRP strengthening with sheet wrapping columns; the second approach is strengthening using CFRP sheets in longitudinal direction of columns, and a third one is a new retrofitting method of near surface mounted (NSM) CFRP strips. Ten full scale specimens with rectangular cross sections dimensions (210 × 150 mm) were tested under eccentric compressive loading to failure. The total length of...
The flexural behavior of 28 beams was experimentally investigated, with an emphasis placed on the... more The flexural behavior of 28 beams was experimentally investigated, with an emphasis placed on the determination of the effects of the slurry infiltrated mat concrete (SIMCON) addition on the flexural response of SIMCON retrofitted and SIMCON repaired concrete beams. The complete flexural behavior of SIMCON retrofitted and repaired beams has been investigated and documented. All beams were subjected to third point flexural loading tests. The experimental results obtained for the SIMCON reparied and retrofitted beams were compared to the results of the reference beams. The general behavior and the benefits of the addition of SIMCON on parameters such as moment curvature, load deflection, ductility, toughness, and energy absorption were experimentally determined.
Rebars in reinforced concrete (RC) slab-column structures may corrode under unfavourable conditio... more Rebars in reinforced concrete (RC) slab-column structures may corrode under unfavourable conditions, making slab-column joints (SCJs) more susceptible to punching shear (PS) failure. Moreover, PS failure is a common brittle failure, which makes it more difficult to evaluate slab column systems' functioning and failure probability. Thus, the prediction of PS resistance and the related reliability analysis are key factors for building RC slab-column systems. In this study, a highfidelity finite-element model was created using Abaqus. A comprehensive experimental record is compiled for corroded RC slab-column joints subjected to punching shear loading. Then, effective parameters are established by applying
Concrete is a non-homogeneous material and it has high compressive strength but it is weak in ten... more Concrete is a non-homogeneous material and it has high compressive strength but it is weak in tension. Cracks occur when tensile stresses exceeded. Improving of concrete properties by adding steel fibers to plain concrete to overcome the weakness of concrete. In this paper steel fibers (S.F) is added with (1mm) diameter and (50mm) long i.e. spect ratio (l/d=50) to plain concrete to study its effect on properties of concrete (workability, compressive strength, splitting tensile strength, flexural strength, abrasion resistance, and absorption). The tested variables are characteristics of concrete (fcu30MPa and fcu40MPa) with steel fibers content (0.4%, 0.5%, and 0.6%) by volume of concrete, and all specimens are tested at 28 days. The results show an increases in compressive strength by (6%, 12 % and 17%) for fcu30 MPa and (8%, 13% and 16%) for fcu40 MPa for fiber content 0.4, 0.5 and 0.6% respectively. The tensile strength increases by (38%, 59% and 67%) for fcu30 and (21%, 35%, 53%)...
Strengthening of R.C columns using the fiber reinforced polymers materials is the most important ... more Strengthening of R.C columns using the fiber reinforced polymers materials is the most important rehabilitation processes. This technique may view as an elective solution for the customary material for reinforcing of concrete structures. Experimental study is designed to test six specimens strengthen with FRP and compare with numerical results of specimens by a finite element models. The tested columns were categorized into two groups based on the column shape. The first contains three circular columns with 200 mm diameter and the second contains three square columns with200 mm length; control specimen, specimen partially strengthened by glass fiber reinforced polymers strip and specimen totally strengthened by glass fiber reinforced polymers sheet. Each column is 1000 mm high, 4ø12mm reinforcement, and ø6@200 mm stirrups. ABAQUS is used to make 18 specimens' numerical model. Both experimental and numerical analyses demonstrate that externally restricted FRP sheets are significant in improving the strength and ductility of the short concrete columns. A design equation is proposed to calculate the ultimate axial load for short concrete columns strengthening by GFRP total wrap.
Proceedings of the Institution of Civil Engineers - Construction Materials, 2011
The objective of the reported study was to investigate and evaluate the behaviour of one-way conc... more The objective of the reported study was to investigate and evaluate the behaviour of one-way concrete slabs reinforced with glass-fibre-reinforced polymer (GFRP) rebars under distributed and line loads. A fibre-reinforced polymer (FRP) composite made with resin-impregnated continuous fibres is considered a promising alternative to traditional steel reinforcement. The experimental programme used eight GFRP concrete slabs to study the type of rebar (steel and GFRP), strength of concrete (25 and 45 MPa), reinforcement ratio and type of loading (distributed and line) loads. The results from a series of tests showed that strains of GFRP rebars are generally larger than those of steel rebars, increasing the ratios of the GFRP rebars led to an increase in ultimate flexural strength and increasing the concrete strength of the slabs led to an increase in slab rigidity, which improves flexural capacity. Furthermore, it was found that failure of slabs reinforced with GFRP rebars occurred by cr...
Concrete has been developed in several ways to avoid environmental contamination and improve the ... more Concrete has been developed in several ways to avoid environmental contamination and improve the quality and properties of concrete by replacing some cement with products from other industrial processes such as pozzolanic materials, including nano-silica (NS). The aim was to improve the concrete properties by filling the spaces between the cement particles, resulting in more dense and stronger concrete by using an ultrasonic device to prevent the nano-silica particles from agglomeration and to ensure their dispersion when the mixture was moistened with water. The effect of partial replacement of cement by nano-silica (NS) was studied by making several concrete mixtures with multiple ratios of nano-silica (NS), the ideal ratio was when using 1% nano-silica (NS) which increased the compressive strength of concrete by 8.5%, then. The behavior of 7 inverted concrete T-beams was studied and they were divided into three groups. In terms of nano-silica impact and change of reinforcement ra...
International Journal of Civil and Structural Engineering, 2010
This paper presents the results of an experimental investigation of the axial behavior of small s... more This paper presents the results of an experimental investigation of the axial behavior of small scale square reinforced concrete columns with fiber reinforced polymer (FRP) bars, as a solution to overcome the corrosion problems, where this material represents a relatively new technology; therefore much research is needed to determine its characteristics and gain confidence to be accepted by engineers for practical application. A series of 8-column was tested in a vertical position and under compressive axial static loading. Where all columns had the same dimensions 250*250mm and 1250mm height, main reinforcement 4#12mm, 6#12mm, and 8#12mm, the transverse reinforcement was o6@120mm closed stirrups along column. The major parameters included in this research were the main reinforcement ratios, the main reinforcement types, the transverse reinforcement ratios in the column, and the characteristic strength of concrete. Results from a series of tests on small-scale specimens showed that ...
This paper presents experimental andnumericalstudy of the flexural behavior of concrete beams wit... more This paper presents experimental andnumericalstudy of the flexural behavior of concrete beams with steel slag as a coarse aggregate partiallyreplacement, and reinforcedby glass fiber reinforced polymers (GFRP) barsby pultrusion process as a solution to overcome the corrosion problem. A series of 10 experimental beams are cast and tested up to failure undertwo-pointload with 600 mm apart, where all beams had the same dimensions with width, depth, total length and clear span between two supports are 100mm, 200mm, 2000mm and 1800mm, respectively. Afinite element analysis program (ANSYS) is used to develop a calibration models for simulation of the behavior of experimentalbeams to give confidence in the use of ANSYS. Then a series of 16 beams models with different parameters (flexure and compression reinforcement ratio and type and shear reinforcement) are used to study how different parameters affect on the behavior of a concrete beam with steel slag and investigate how GFRP should be ...
Fire could dramatically reduce strength of reinforced concrete columns. The objective of this wor... more Fire could dramatically reduce strength of reinforced concrete columns. The objective of this work is to study columns exposed to fire under axial load and to evaluate reduction in column compressive capacity after fire. The first part of this research is experimental investigation of fifteencolumn specimens (15 • 15 • 100) cm exposed except one specimen to (600°C) fire. The second part is a theoretical analysis performed using three-dimensional nonlinear finite element program. The main studied parameters were concrete strength, fire duration, level of applied loads, longitudinal reinforcement yield strength, percentage of longitudinal reinforcement, and bar diameters. Comparison between experimental results and theoretical analysis indicated that for columns not exposed to fire, the first crack appeared at 80% of column failure load while the first crack occurred at 50% of column failure load for columns exposed to fire. Columns with the same reinforcement percentage but with smaller bar diameters gained less lateral strain and smaller vertical displacement than columns with bigger bar diameters. Using high-grade steel as main reinforcement showed failure load higher by 55% than that of column reinforced by mild steel. Cooling column by jet water resulted in 17% reduction in failure load than columns cooling gradually in room temperature.
Degradation in reinforced concrete (RC) members associated with rebar corrosion in old buildings ... more Degradation in reinforced concrete (RC) members associated with rebar corrosion in old buildings is one major concern that can significantly affect the strength and serviceability of RC structures. Strengthening existing structures using FRP can comprise complex assessment and design processes. This study addresses the critical issue of modeling the behavior associated with steel reinforcement corrosion in RC slab-column joints (SCJs). Three modeling methods, namely artificial neural network (ANN), Eureqa’s symbolic regression algorithm, and analytical modeling, are proposed to predict the punching shear (PS) capacity of corroded RC SCJs by accounting for the changes in material properties due to corrosion and the strengthening provided by different types of FRP. The accuracy of the proposed models is validated through comparisons with experimental results and a verified finite element (FE) model that considers material deterioration and bond degradation. The results demonstrate that the proposed models offer more accurate PS capacity predictions than existing design codes. Among the considered prediction models, the ANN model exhibits superior performance and is recommended for PS capacity prediction. A practical design tool in the form of a graphical user interface (GUI) was created to facilitate the assessment and prediction of the PS behavior of corroded RC SCJs. Engineers can conveniently use this GUI to evaluate and predict the performance of such joints.
International Journal of Civil and Structural Engineering, 2011
In this paper, the results of an analytical investigation on the behavior of RC columns reinforce... more In this paper, the results of an analytical investigation on the behavior of RC columns reinforced with fiber reinforced polymer bars FRP are presented and discussed. Nonlinear finite element analysis on 10column specimens was achieved by using ANSYS software. The nonlinear finite element analysis program ANSYS is utilised owing to its capabilities to predict either the response of reinforced concrete columns in the postelastic range or the ultimate strength of a reinforced concrete columns reinforced by FRP bars. An extensive set of parameters is investigated including different main reinforcement ratios, main reinforcement types (GFRP, Steel), the transverse reinforcement ratios, and the characteristic compressive strength of concrete. A comparison between the experimental results and those predicted by the existing models are presented. Results and conclusions may be useful for designers, have been raised, and represented.
This paper studied the reinforced concrete (RC) slender columns with rectangular sections behavio... more This paper studied the reinforced concrete (RC) slender columns with rectangular sections behavior when strengthened by carbon fiber reinforced polymers (CFRPs) and exposed to eccentric loads. Nine specimens with a rectangular slender cross-section (210x150mm) were tested with lengths of 3000mm (λ= 70), 2500mm (λ= 58), and 2000mm (λ= 46). Samples were fabricated as slender columns using two strategies. The first strategy is CFRP strengthening with near-surface mounted longitudinally (L-NSM) CFRP strips. The second strategy is composed of a new method where longitudinal near surface mounted (L-NSM) CFRP strips is retrofitted with transverse CFRP sheet wrapping. And the results were used to explore the impact of CFRP retrofitting techniques on the columns. A numerical investigation was performed to examine further key variables' effects on RC columns, demonstrating acceptable outcome with the experimental findings. For all tests, specimens were loaded under compressive axial static. The compression force was applied at an initial eccentricity of 35 mm. Moreover, based on the experimental results of the current investigation, the validated models were used in a comprehensive parametric study comprising fifteen new analytical models to check the effects of key variables expected to impact the behavior of NSM and CFRP-confined RC columns. The key conclusions the study provided are that CFRP retrofitting techniques can enhance axial and flexural rigidity and improve the RC columns performance. Additionally, the study revealed that different retrofitting techniques had different impacts on the RC columns behavior, depending on the slender.
International Journal of Advanced Structural Engineering, Dec 1, 2011
In this paper, the results of an analytical investigation on the behavior of RC columns reinforce... more In this paper, the results of an analytical investigation on the behavior of RC columns reinforced with fiber reinforced polymer bars FRP are presented and discussed. Nonlinear finite element analysis on 10column specimens was achieved by using ANSYS software. The nonlinear finite element analysis program ANSYS is utilised owing to its capabilities to predict either the response of reinforced concrete columns in the postelastic range or the ultimate strength of a reinforced concrete columns reinforced by FRP bars. An extensive set of parameters is investigated including different main reinforcement ratios, main reinforcement types (GFRP, Steel), the transverse reinforcement ratios, and the characteristic compressive strength of concrete. A comparison between the experimental results and those predicted by the existing models are presented. Results and conclusions may be useful for designers, have been raised, and represented.
The behavior of reinforced concrete columns with holes under axial load is not understood, and re... more The behavior of reinforced concrete columns with holes under axial load is not understood, and researches in the subject are needed to help designers and structural code officials. Holes drilled out to install additional services or equipment, such as for ducts through columns, beams, or walls, can lead to loss of strength and possible structural failure. Until now little work has been done on holes in columns and, hence, this study aims to examine the amount of strength lost due to the presence of holes in columns. Nonlinear finite element analysis on 21-column specimens was achieved by using ANSYS software. The nonlinear finite element analysis program ANSYS is utilized owing to its capabilities to predict either the response of reinforced concrete columns in the post-elastic range or the ultimate strength of reinforced concrete columns. An extensive set of parameters is investigated including different parameters; dimensions of the holes with diameter 0.1, 0.15, 0.2 and 0.3 of column length, their relative position in columns, and the shape of holes; circle and square. A comparison between the experimental results and those predicted by the existing models are presented. Results and conclusions may be useful for designers, have been raised, and represented. Keyword: Inelastic finite element analysis, columns, holes, strength and testing of materials.
In this paper, the results of an analytical investigation on the behavior of RC columns reinforce... more In this paper, the results of an analytical investigation on the behavior of RC columns reinforced with fiber reinforced polymer bars FRP are presented and discussed. Nonlinear finite element analysis on 10column specimens was achieved by using ANSYS software. The nonlinear finite element analysis program ANSYS is utilised owing to its capabilities to predict either the response of reinforced concrete columns in the postelastic range or the ultimate strength of a reinforced concrete columns reinforced by FRP bars. An extensive set of parameters is investigated including different main reinforcement ratios, main reinforcement types (GFRP, Steel), the transverse reinforcement ratios, and the characteristic compressive strength of concrete. A comparison between the experimental results and those predicted by the existing models are presented. Results and conclusions may be useful for designers, have been raised, and represented.
Strengthening of existing Reinforced Concrete structures is becoming a major issue in civil engin... more Strengthening of existing Reinforced Concrete structures is becoming a major issue in civil engineering. Externally Bonded Reinforcement (EBR) systems have been successfully applied for strengthening of existing concrete structures. This work includes a results of numerical models carried to investigate the behavior of reinforced concrete, RC, slender columns with rectangular sections under the effect of eccentric loads strengthened with carbon fiber-reinforced polymers (CFRPs) in three different manners in order to enhance its axial and flexural rigidity. The first approach is a well-known form of CFRP strengthening with sheet wrapping columns; the second approach is strengthening using CFRP sheets in longitudinal direction of columns, and a third one is a new retrofitting method of near surface mounted (NSM) CFRP strips. Ten full scale specimens with rectangular cross sections dimensions (210 × 150 mm) were tested under eccentric compressive loading to failure. The total length of...
The flexural behavior of 28 beams was experimentally investigated, with an emphasis placed on the... more The flexural behavior of 28 beams was experimentally investigated, with an emphasis placed on the determination of the effects of the slurry infiltrated mat concrete (SIMCON) addition on the flexural response of SIMCON retrofitted and SIMCON repaired concrete beams. The complete flexural behavior of SIMCON retrofitted and repaired beams has been investigated and documented. All beams were subjected to third point flexural loading tests. The experimental results obtained for the SIMCON reparied and retrofitted beams were compared to the results of the reference beams. The general behavior and the benefits of the addition of SIMCON on parameters such as moment curvature, load deflection, ductility, toughness, and energy absorption were experimentally determined.
Rebars in reinforced concrete (RC) slab-column structures may corrode under unfavourable conditio... more Rebars in reinforced concrete (RC) slab-column structures may corrode under unfavourable conditions, making slab-column joints (SCJs) more susceptible to punching shear (PS) failure. Moreover, PS failure is a common brittle failure, which makes it more difficult to evaluate slab column systems' functioning and failure probability. Thus, the prediction of PS resistance and the related reliability analysis are key factors for building RC slab-column systems. In this study, a highfidelity finite-element model was created using Abaqus. A comprehensive experimental record is compiled for corroded RC slab-column joints subjected to punching shear loading. Then, effective parameters are established by applying
Concrete is a non-homogeneous material and it has high compressive strength but it is weak in ten... more Concrete is a non-homogeneous material and it has high compressive strength but it is weak in tension. Cracks occur when tensile stresses exceeded. Improving of concrete properties by adding steel fibers to plain concrete to overcome the weakness of concrete. In this paper steel fibers (S.F) is added with (1mm) diameter and (50mm) long i.e. spect ratio (l/d=50) to plain concrete to study its effect on properties of concrete (workability, compressive strength, splitting tensile strength, flexural strength, abrasion resistance, and absorption). The tested variables are characteristics of concrete (fcu30MPa and fcu40MPa) with steel fibers content (0.4%, 0.5%, and 0.6%) by volume of concrete, and all specimens are tested at 28 days. The results show an increases in compressive strength by (6%, 12 % and 17%) for fcu30 MPa and (8%, 13% and 16%) for fcu40 MPa for fiber content 0.4, 0.5 and 0.6% respectively. The tensile strength increases by (38%, 59% and 67%) for fcu30 and (21%, 35%, 53%)...
Strengthening of R.C columns using the fiber reinforced polymers materials is the most important ... more Strengthening of R.C columns using the fiber reinforced polymers materials is the most important rehabilitation processes. This technique may view as an elective solution for the customary material for reinforcing of concrete structures. Experimental study is designed to test six specimens strengthen with FRP and compare with numerical results of specimens by a finite element models. The tested columns were categorized into two groups based on the column shape. The first contains three circular columns with 200 mm diameter and the second contains three square columns with200 mm length; control specimen, specimen partially strengthened by glass fiber reinforced polymers strip and specimen totally strengthened by glass fiber reinforced polymers sheet. Each column is 1000 mm high, 4ø12mm reinforcement, and ø6@200 mm stirrups. ABAQUS is used to make 18 specimens' numerical model. Both experimental and numerical analyses demonstrate that externally restricted FRP sheets are significant in improving the strength and ductility of the short concrete columns. A design equation is proposed to calculate the ultimate axial load for short concrete columns strengthening by GFRP total wrap.
Proceedings of the Institution of Civil Engineers - Construction Materials, 2011
The objective of the reported study was to investigate and evaluate the behaviour of one-way conc... more The objective of the reported study was to investigate and evaluate the behaviour of one-way concrete slabs reinforced with glass-fibre-reinforced polymer (GFRP) rebars under distributed and line loads. A fibre-reinforced polymer (FRP) composite made with resin-impregnated continuous fibres is considered a promising alternative to traditional steel reinforcement. The experimental programme used eight GFRP concrete slabs to study the type of rebar (steel and GFRP), strength of concrete (25 and 45 MPa), reinforcement ratio and type of loading (distributed and line) loads. The results from a series of tests showed that strains of GFRP rebars are generally larger than those of steel rebars, increasing the ratios of the GFRP rebars led to an increase in ultimate flexural strength and increasing the concrete strength of the slabs led to an increase in slab rigidity, which improves flexural capacity. Furthermore, it was found that failure of slabs reinforced with GFRP rebars occurred by cr...
Concrete has been developed in several ways to avoid environmental contamination and improve the ... more Concrete has been developed in several ways to avoid environmental contamination and improve the quality and properties of concrete by replacing some cement with products from other industrial processes such as pozzolanic materials, including nano-silica (NS). The aim was to improve the concrete properties by filling the spaces between the cement particles, resulting in more dense and stronger concrete by using an ultrasonic device to prevent the nano-silica particles from agglomeration and to ensure their dispersion when the mixture was moistened with water. The effect of partial replacement of cement by nano-silica (NS) was studied by making several concrete mixtures with multiple ratios of nano-silica (NS), the ideal ratio was when using 1% nano-silica (NS) which increased the compressive strength of concrete by 8.5%, then. The behavior of 7 inverted concrete T-beams was studied and they were divided into three groups. In terms of nano-silica impact and change of reinforcement ra...
International Journal of Civil and Structural Engineering, 2010
This paper presents the results of an experimental investigation of the axial behavior of small s... more This paper presents the results of an experimental investigation of the axial behavior of small scale square reinforced concrete columns with fiber reinforced polymer (FRP) bars, as a solution to overcome the corrosion problems, where this material represents a relatively new technology; therefore much research is needed to determine its characteristics and gain confidence to be accepted by engineers for practical application. A series of 8-column was tested in a vertical position and under compressive axial static loading. Where all columns had the same dimensions 250*250mm and 1250mm height, main reinforcement 4#12mm, 6#12mm, and 8#12mm, the transverse reinforcement was o6@120mm closed stirrups along column. The major parameters included in this research were the main reinforcement ratios, the main reinforcement types, the transverse reinforcement ratios in the column, and the characteristic strength of concrete. Results from a series of tests on small-scale specimens showed that ...
This paper presents experimental andnumericalstudy of the flexural behavior of concrete beams wit... more This paper presents experimental andnumericalstudy of the flexural behavior of concrete beams with steel slag as a coarse aggregate partiallyreplacement, and reinforcedby glass fiber reinforced polymers (GFRP) barsby pultrusion process as a solution to overcome the corrosion problem. A series of 10 experimental beams are cast and tested up to failure undertwo-pointload with 600 mm apart, where all beams had the same dimensions with width, depth, total length and clear span between two supports are 100mm, 200mm, 2000mm and 1800mm, respectively. Afinite element analysis program (ANSYS) is used to develop a calibration models for simulation of the behavior of experimentalbeams to give confidence in the use of ANSYS. Then a series of 16 beams models with different parameters (flexure and compression reinforcement ratio and type and shear reinforcement) are used to study how different parameters affect on the behavior of a concrete beam with steel slag and investigate how GFRP should be ...
Fire could dramatically reduce strength of reinforced concrete columns. The objective of this wor... more Fire could dramatically reduce strength of reinforced concrete columns. The objective of this work is to study columns exposed to fire under axial load and to evaluate reduction in column compressive capacity after fire. The first part of this research is experimental investigation of fifteencolumn specimens (15 • 15 • 100) cm exposed except one specimen to (600°C) fire. The second part is a theoretical analysis performed using three-dimensional nonlinear finite element program. The main studied parameters were concrete strength, fire duration, level of applied loads, longitudinal reinforcement yield strength, percentage of longitudinal reinforcement, and bar diameters. Comparison between experimental results and theoretical analysis indicated that for columns not exposed to fire, the first crack appeared at 80% of column failure load while the first crack occurred at 50% of column failure load for columns exposed to fire. Columns with the same reinforcement percentage but with smaller bar diameters gained less lateral strain and smaller vertical displacement than columns with bigger bar diameters. Using high-grade steel as main reinforcement showed failure load higher by 55% than that of column reinforced by mild steel. Cooling column by jet water resulted in 17% reduction in failure load than columns cooling gradually in room temperature.
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