To retrofit and strengthen existing unreinforced masonry (URM) structures to resist the potential earthquake damages has become an important issue in Australia. In order to secure the performance of URM under seismic ...To retrofit and strengthen existing unreinforced masonry (URM) structures to resist the potential earthquake damages has become an important issue in Australia. In order to secure the performance of URM under seismic loading in the future, a research project was carried out aimed at developing a simple and high strength seismic retrofitting technique for masonry structures. A series of experimental testing on URM walls retrofitted with an innovative technique by cable system have been conducted. The results indicated that both the strength and ductility of the tested speci-mens were significantly enhanced with the technique. An analytical model which is based on Dis-tinct Element Method (DEM) has also been developed to simulate the behaviour of URM walls be-fore and after retrofitting. The model is then further developed by applying a seismic wave to the wall to simulate the wall behavior under earthquake loads before and after retrofitting.展开更多
Optimization of design features of reinforced sheet is investigated. Initially, equations governing composite structures are extracted based on Kirchhoff sheet model under bending using Hamilton's principal. Then,...Optimization of design features of reinforced sheet is investigated. Initially, equations governing composite structures are extracted based on Kirchhoff sheet model under bending using Hamilton's principal. Then, design parameters for the composite structure are extracted with simple supportive boundary conditions from proposed solution. Next, optimization is achieved by determining dimensions of a reinforced sheet specimen. Weight optimization of reinforced sheet structure has been obtained based on variations in thickness and number of longitudinal and transverse reinforcements. Buckling static characteristic is utilized in optimization process. To solve the extracted equations, semi-analytical method of CS-DSG3 has been applied. Results are presented in graphs that show variation of design parameters by changing the geometric parameters. ABAQUS software has been used for design verification. The results show that an increase in thickness of 3 mm skip value tends to be zero. Also, there is a change in the amount of deflection for sheets with a minimum thickness of 3 mm by increasing the number of longitudinal and transverse reinforcement. There is a good agreement between the numerical method of finite elements and the method X-FEM-DSG3.展开更多
Very high concentration of flexural, shear and torsional stresses occurs at the wall-slab junctions in a laterally loaded tall building consisting of planar walls and coupling slabs. Due to this concentration of stres...Very high concentration of flexural, shear and torsional stresses occurs at the wall-slab junctions in a laterally loaded tall building consisting of planar walls and coupling slabs. Due to this concentration of stresses and their interaction, there are great chances of failure to occur at the junction. Also the flexural stresses are not uniformly distributed and have the highest intensity near the periphery of inner walls but are reduced drastically as we move away from the wall-slab junction. Numerous attempts have been made to strengthen the wall-slab junction by using various types of shear reinforcement to ensure that shear failure should not occur. Various methods including fibre reinforcement consisting of twins of twisted steel couplets have already been used. This paper describes a new method of placing 2 inch wide flange I-sections at appropriate locations to improve the shear strength of the wall-slab junctions. Based on systematic research, a new procedure has also been developed to assess the strength of wall-slab junction using the new reinforcement method. Test results showed that a substantial increase, up to 57%, in the shear strength of specimens was obtained by using the new method of shear reinforcement in a laterally loaded tall building.展开更多
The shear performance, modes of failure, and strain analysis of simply supported reinforced concrete （RC） T-beams, externally strengthened in shear using epoxy bonded glass fiber reinforced polymer （GFRP） strips a...The shear performance, modes of failure, and strain analysis of simply supported reinforced concrete （RC） T-beams, externally strengthened in shear using epoxy bonded glass fiber reinforced polymer （GFRP） strips are focused in the present paper. Six RC T-beams of 2.5 m span without shear reinforcement are cast. Three beams are used as control specimens and rest three beams are strengthened in shear with GFRP strips in U-shape, side bonded at 45° and 90° to the longitudinal axis of the beam. All the beams are tested in a Universal Testing Machine. The test results demonstrate the feasibility of using an externally applied, epoxy-bonded GFRP strips to restore or increase the shear strength of RC T-beams. It is also observed that the RC T-beams strengthened by diagonal side strips outperformed those strengthened with vertical side strips.展开更多
This paper deals with flexural concrete members reinforced longitudinally but without transverse reinforcement. The conducted experimental investigations have shown that beams without web reinforcement may fail withou...This paper deals with flexural concrete members reinforced longitudinally but without transverse reinforcement. The conducted experimental investigations have shown that beams without web reinforcement may fail without attaining their full flexural capacity and then shear governs their failure. In the paper, there are presented recent results of the author＇s own experiments, which aimed at disclosing some aspects of the propagation of cracks in longitudinally reinforced concrete beams without stirrups. The experimental program has been designed especially to investigate the influence of the shear span-to-depth ratio on diagonal crack propagation and load carrying capacity of tested beams.展开更多
文摘To retrofit and strengthen existing unreinforced masonry (URM) structures to resist the potential earthquake damages has become an important issue in Australia. In order to secure the performance of URM under seismic loading in the future, a research project was carried out aimed at developing a simple and high strength seismic retrofitting technique for masonry structures. A series of experimental testing on URM walls retrofitted with an innovative technique by cable system have been conducted. The results indicated that both the strength and ductility of the tested speci-mens were significantly enhanced with the technique. An analytical model which is based on Dis-tinct Element Method (DEM) has also been developed to simulate the behaviour of URM walls be-fore and after retrofitting. The model is then further developed by applying a seismic wave to the wall to simulate the wall behavior under earthquake loads before and after retrofitting.
文摘Optimization of design features of reinforced sheet is investigated. Initially, equations governing composite structures are extracted based on Kirchhoff sheet model under bending using Hamilton's principal. Then, design parameters for the composite structure are extracted with simple supportive boundary conditions from proposed solution. Next, optimization is achieved by determining dimensions of a reinforced sheet specimen. Weight optimization of reinforced sheet structure has been obtained based on variations in thickness and number of longitudinal and transverse reinforcements. Buckling static characteristic is utilized in optimization process. To solve the extracted equations, semi-analytical method of CS-DSG3 has been applied. Results are presented in graphs that show variation of design parameters by changing the geometric parameters. ABAQUS software has been used for design verification. The results show that an increase in thickness of 3 mm skip value tends to be zero. Also, there is a change in the amount of deflection for sheets with a minimum thickness of 3 mm by increasing the number of longitudinal and transverse reinforcement. There is a good agreement between the numerical method of finite elements and the method X-FEM-DSG3.
文摘Very high concentration of flexural, shear and torsional stresses occurs at the wall-slab junctions in a laterally loaded tall building consisting of planar walls and coupling slabs. Due to this concentration of stresses and their interaction, there are great chances of failure to occur at the junction. Also the flexural stresses are not uniformly distributed and have the highest intensity near the periphery of inner walls but are reduced drastically as we move away from the wall-slab junction. Numerous attempts have been made to strengthen the wall-slab junction by using various types of shear reinforcement to ensure that shear failure should not occur. Various methods including fibre reinforcement consisting of twins of twisted steel couplets have already been used. This paper describes a new method of placing 2 inch wide flange I-sections at appropriate locations to improve the shear strength of the wall-slab junctions. Based on systematic research, a new procedure has also been developed to assess the strength of wall-slab junction using the new reinforcement method. Test results showed that a substantial increase, up to 57%, in the shear strength of specimens was obtained by using the new method of shear reinforcement in a laterally loaded tall building.
文摘The shear performance, modes of failure, and strain analysis of simply supported reinforced concrete （RC） T-beams, externally strengthened in shear using epoxy bonded glass fiber reinforced polymer （GFRP） strips are focused in the present paper. Six RC T-beams of 2.5 m span without shear reinforcement are cast. Three beams are used as control specimens and rest three beams are strengthened in shear with GFRP strips in U-shape, side bonded at 45° and 90° to the longitudinal axis of the beam. All the beams are tested in a Universal Testing Machine. The test results demonstrate the feasibility of using an externally applied, epoxy-bonded GFRP strips to restore or increase the shear strength of RC T-beams. It is also observed that the RC T-beams strengthened by diagonal side strips outperformed those strengthened with vertical side strips.
文摘This paper deals with flexural concrete members reinforced longitudinally but without transverse reinforcement. The conducted experimental investigations have shown that beams without web reinforcement may fail without attaining their full flexural capacity and then shear governs their failure. In the paper, there are presented recent results of the author＇s own experiments, which aimed at disclosing some aspects of the propagation of cracks in longitudinally reinforced concrete beams without stirrups. The experimental program has been designed especially to investigate the influence of the shear span-to-depth ratio on diagonal crack propagation and load carrying capacity of tested beams.
