低轴压比下预制边缘构件双面叠合剪力墙抗震性能试验研究

Experimental study on seismic behavior of double-superimposed shear walls with prefabricated boundary elements under low axial force ratio

预制边缘构件双面叠合剪力墙是一种预制率更高的装配式剪力墙,针对底部拼缝处变形集中问题,通过1个设计轴压比0.2的预制约束边缘构件与2个设计轴压比0.1的预制构造边缘构件的双面叠合剪力墙高墙足尺(高宽比为2.0)的低周水平往复加载试验,分析轴压比、边缘构件形式与底部搭接区纵筋插筋面积增加率(0%、25%与33%)对该类剪力墙抗震性能的影响。试验结果表明:剪力墙均发生了预期的弯曲破坏模式,增加插筋面积的2个双面叠合剪力墙弯剪裂缝分布更加均匀,实现了墙体损伤区由墙底水平接缝区向钢筋搭接区上部的转移,可以有效控制底部接缝区的变形与墙体损伤集中问题;滞回曲线均较饱满,增加插筋面积后剪力墙滞回环更为饱满,刚度退化减缓,耗能能力强;受弯承载力实测值为预测值的1.06~1.21倍,插筋面积增加33%的剪力墙峰值荷载提高了12%;增加插筋面积后,当剪力墙达到峰值荷载时,位移角约为1/80,而未增加插筋面积剪力墙的相应位移角约为1/140,极限位移角均大于1/70,满足我国设计规范中罕遇地震作用下剪力墙的变形能力要求。

Double-superimposed shear wall with prefabricated boundary elements( DSWPBE) is an assembled shear wall with high precast ratio. Regarding its local deflection concentration near the bottom seam,a double-superimposed shear wall with appropriate increment ratio on overlapping reinforcement area was designed. To research the seismic performance of this wall,experimental study on seismic behavior of three DSWPBE full scale specimens with height to depth ratio of 2. 0 under lower axial force ratio was conducted. Three specimens included one specimen with confined boundary elements under axial force ratio of 0. 2 and two specimens with construction boundary elements under axial force ratio of 0. 1. The influences of axial force ratio,boundary element form and increment ratio of overlapping reinforcement area( 0%,25% and 33%) on specimens were analyzed. The test results indicate that all specimens fail in flexural failure mode. Two specimens with increment of the overlapping reinforcement area have more cracks and distribute more symmetrically and uniformly. Increasing the overlapping reinforcement can effectively shift the wall damage zone from the bottom horizontal joint to the top zone of the overlapping bars in the boundary elements. The local deflection concentration and local damage near the bottom have been controlled significantly. The hysteretic curves of all specimens are quite plump but the curves of specimens with increment of the overlapping reinforcement area are plumper,the stiffness degradation is decreased and the energy consumption capacity is improved. The moment resisting capacity of the specimens is about 1. 06 ~ 1. 21 times of the predicted value. The peak load of the specimen with 33% increment of the overlapping reinforcement area increases about 12%. The drift ratio at peak load is about1/80 and 1/140 for the specimens with and without increment of the overlapping reinforcement area,respectively. The ultimate drift ratios of all specimens are greater than 1/70,which satisfy the design requirement of deformation capacity of reinforced concrete shear walls under rare earthquake level.