| In recent years,due to frequent earthquakes,higher requirements have been put forward for seismic design of buildings.Shear wall,as the most critical lateral component,bears the main horizontal and vertical loads of the structure.Once damaged,it will endanger the safety of the whole structure.Therefore,it is particularly important to study the mechanical properties of shear wall members and develop shear walls with high bearing capacity,high stiffness,strong energy dissipation and good ductility.One of the most effective methods to improve the seismic performance of shear walls is to improve the common shear walls,reconfigure the reinforced skeleton of the walls and improve the binding force of the reinforced skeleton on the concrete in the core area.Therefore,in this paper,column binding was used to improve the binding force of concrete in the core area.In addition,reasonable setting of inclined bars could improve the ductility and energy dissipation capacity of shear wall,and had an impact on its failure mechanism.Therefore,a new type of shear wall with oblique reinforcement was proposed in this paper,the low-cycle repeated test and seismic damage analysis were taken.ABAQUS finite element simulation and load-bearing calculation methods of this new type of shear wall and ordinary shear wall were studied.The main contributions were as follows:1.A reinforced shear wall with oblique bars was proposed and developed.The low-cycle cyclic loading tests of a reinforced shear wall with oblique bars and a reinforced concrete shear wall were carried out.The seismic performance of the shear wall with oblique bars was analyzed in terms of seven aspects,included failure mode,hysteretic curve,skeleton curve,ductility,energy dissipation capacity,stiffness degradation and residual deformation.The seismic mechanism of reinforced column shear wall with oblique shear wall was revealed.2.Two shear wall specimens with different structural forms were calculated and analyzed based on the energy method.The damage index of each controlled displacement load was taken as the quantitative criterion for damage evaluation,and the seismic damage evaluation criterion of reinforced shear wall with oblique bars was established.The influence of the structural form of oblique bars on the seismic damage evolution process of the specimens was analyzed.3.The appropriate constitutive curve of concrete and reinforcement were selected,the column-reinforced shear wall with oblique reinforcement was calculated and analyzed by ABAQUS finite element software,and the load-displacement curve of the specimens under uniaxial load was obtained.Through the analysis of the stress nephogram of reinforcement and Mises stress nephogram of shear wall at each characteristic point on the curve,the column-reinforced shear wall with oblique reinforcement was studied,and the working mechanism of reinforced shear wall specimens during the whole loading process were analyzed.4.Based on the test results of two shear walls with different structural forms under low-cycle repeated load,the restraint mechanism of column-type reinforcement with oblique reinforcement on core concrete was analyzed,the lateral pressure restrained by stirrups was calculated,and the constitutive relationship of confined concrete under uniaxial load proposed by Mander was given.The calculation methods of normal section bearing capacity of two shear wall specimens were given,including crack load,yield load,peak load and failure load,and the calculated values were compared with the experimental values.Based on the experimental results,the following conclusions were drawn:1.Compared with ordinary reinforced shear wall,the seismic performance of column reinforced shear wall with oblique reinforcement was better.It not only had high bearing capacity and lateral stiffness,but also had better displacement ductility and energy dissipation capacity due to the restraint effect of inner column reinforcement on the concrete in core area,which slowed down the degradation rate of bearing capacity and stiffness of shear wall.2.The structure of column reinforced with oblique reinforcement had reduce the seismic damage of shear wall specimens,so that the damage index of ZSW1 specimens was always less than SW1 specimens during the whole loading process,and the established seismic damage evaluation criteria could better reflect the relationship between the damage index and the damage mode of shear wall with oblique reinforcement and ordinary shear wall.3.The yield mechanism of the column reinforced shear wall specimens with oblique bars was as follows: the concrete in the tension zone at the left root of the specimens cracked first,and the stress of the cross oblique bars and the column longitudinal bars increased gradually with the loading,and the stress of the cross oblique bars was greater than that of the column longitudinal bars,and the cross oblique bars yielded first.Then,the stress of the column longitudinal reinforcement at the bottom of the wall continued to increase,the height of the compression zone of the shear wall section decreased,the column longitudinal reinforcement yielded,the concrete at the lower right corner was crushed,and the bearing capacity of the shear wall reached its peak state.Finally,the tensile yield area of the column longitudinal reinforcement at the bottom of the wall increased,both sides of the reinforcement buckled and protruded,and the specimens were damaged.4.Column reinforced concrete is essentially confined concrete with stirrups.The constitutive relationship of column reinforced concrete given in this paper was reasonable and could be used as a reference for the calculation of bearing capacity of this kind of shear wall.The new type of shear wall was simple in structure,convenient in construction and has good practical value.It can be used for shear walls of general high-rise buildings and large complex buildings. |
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