Seismic Performance Of Double-superimposed Shear Wall With Different Axial Force Ratio

Double-superimposed reinforced concrete(RC)shear wall(DRCSW)is one of the semi-assembled shear wall structure.It is composed of two precast RC panels connected by truss bars and cast-in-place concrete layered between them.Horizontal and vertical overlapping bars are placed in cast-in-place panel to connect adjacent precast walls.To study the seismic behavior of DRCSWs,experiment study on 6 DRCSWs and 1 cast-in-place shear wall with height to depth ratio of 2.0 has been presented in this paper.Besides,finite element analysis software ABAQUS has been used to study the influence of different parameters on behavior of DRCSW.Based on the test and finite element results,fabrication and construction suggestions has been proposed.The contributions of this paper contain as following:(1)Through experiment test of 3 DRCSWs and 1 cast-in-place shear wall under design axial force ratio of 0.6,it is found that Double-superimposed shear wall with prefabricated and cast-in-place boundary elements have smilar behavior with cast-in-place shear wall.The failure mode,hysteresis curves,bearing capacity,deformation capacity,energy consumption and stiffness degradation between them did not show significant differences;With the overlapping reinforcement area in the boundary elements increased by 25%,part of the wall damage zone transformed from the horizontal joint to the top zone of the overlapping area.The peak load and displacement of the specimen with 25% increment of the overlapping reinforcement area increased about 7% and 12%,respectively.The ultimate drift ratio of all specimens is greater than 1/120,which satisfies the deformation capacity requirement of reinforced concrete shear walls under design rare earthquake level.(2)Double-superimposed shear wall with prefabricated boundary elements is a high precast ratio assembled structural element.Regard to its local deflection concentration near the wall bottom assembled area,experiment study on seismic behavior of 1 DRCSW with confined prefabricated boundary elements under axial force ratio of 0.2 and 2 DRCSW with construction prefabricated boundary elements under axial force ratio of 0.1 has been carried out.Test results indicate that: with the overlapping reinforcement area increased by more than 25%,specimens had more cracks and cracked more symmetrical and uniformly.Increasing the overlapping reinforcement can effectively lead the wall damage zone from the wall bottom horizontal joint to the top zone of the overlapping area.The local deflection concentration near the horizontal joint have been controlled significantly.The hysteretic curves of two enhanced connection specimens are plumper than unenhanced specimen.The peak load of the specimen with 33% increment of the overlapping reinforcement area increased about 12%.The ultimate drift ratio of all specimens is greater than 1/70,which satisfies the deformation capacity requirement of reinforced concrete shear walls under design rare earthquake level.(3)Based on the experimental result,parameter studies have been carried out by finite element analysis software ABAQUS.The result shows that the effect from the concrete strength variation is more obvious for the DRCSW wall under high axial force ratio.With axial force ratio increasing,the lateral stiffness of the wall before its peak load and its peak load will increase while the its deformation capacity will decrease.Increasing the stirrup ratio in the boundary element increase the deformation capability of the DRCSW.(4)Based on the test and finite element results,the suggestions for fabrication and structural design are proposed.The structural design suggestions are about the horizontal joint and boundary element.It can be a reference for engineering practice.The formula suggested for symmetrically reinforced wingless DRCSW can predict the bearing capacity properly.