基于IDA的自复位预制剪力墙抗倒塌能力分析

Collapse Capacity Analysis of Self-centering Precast Shear Walls Based on IDA

自复位预制混凝土剪力墙通过预应力筋将分段预制墙片沿竖向拼接形成整体,同时在墙底部设置普通钢筋以增加耗能能力。前期的试验研究和数值模拟结果表明,自复位预制混凝土剪力墙具有损伤破坏程度轻、震后残余变形小的特点,是具有震后可恢复功能的抗震结构体系。为进一步研究该类体系在强地震动输入下的性能,特别是抗倒塌性能,设计了4层和6层原型结构,分别采用自复位预制混凝土剪力墙和传统钢筋混凝土剪力墙作为主要抗侧力构件。通过前期试验结果,建立了可靠的数值分析模型,用于后续倒塌分析。采用44条地震动输入对各原型结构进行非线性增量动力时程分析,并建立各自的倒塌易损性曲线,在此基础上采用FEMA P695标准评估和比较各原型结构的抗倒塌能力。分析结果表明,由于耗能能力略小的原因,自复位预制混凝土剪力墙在罕遇地震作用下的水平位移比传统现浇剪力墙稍大,但其在强震作用后的残余变形则明显小于普通钢筋混凝土剪力墙,即具备良好的震后自复位性能。倒塌易损性曲线的对比表明自复位预制剪力墙的变形能力显著优于普通剪力墙,因此震后损伤破坏程度轻。采用FEMA P695标准的方法对各原型结构抗倒塌能力评估结果表明,作者设计的4层和6层自复位预制剪力墙具有与普通现浇剪力墙接近的抗倒塌能力和地震安全冗余度,满足FEMA P695对结构抗倒塌安全性的要求。

Self-centering precast concrete shear walls were constructed by using post-tensioning strands to assemble prefabricated wall panels along vertical direction.At the base of the wall,conventional reinforcing steel was used for increasing energy dissipation capability.It was concluded from the previous experimental and numerical studies that both structural damage and residual deformation for a self-centering precast concrete shear wall is insignificant,which means an resilience after a major seismic event for this type of structural system.To further investigate the performance of this system under severe earthquakes,particularly the performance for collapse resistance,two prototype structures of four and six stories were designed using self-centering precast concrete wall and conventional reinforced concrete wall as the primary lateral force resisting system,respectively.Nonlinear incremental dynamic history analyses were performed using 44 ground motions,and the results were used to establish the collapse fragility curves.On the basis of this,the collapse capacities of the above prototype structures were evaluated and compared according to the FEMA P695 standard.The analytical results showed that the self-centering precast concrete shear walls exhibit slightly larger lateral displacement than the conventional reinforced concrete shear walls because of relatively less energy dissipation capacity.However,the residual lateral displacements for the self-centering precast concrete shear walls are much less than their counterparts,indicating good self-centering capability.Based on the comparison of collapse fragility curves,it was concluded that the deformation capacity for a self-centering precast concrete shear wall is much better than a conventional reinforced concrete wall,resulting in significantly less damage after an earthquake event.The results from collapse capacity evaluation using the FEMA P695 standard indicate that the self-centering precast concrete walls investigated in this study have a similar seismic collapse capacity and safety redundancy compared to the designed conventional reinforced concrete walls,while also fulfill the requirements for structural collapse safety as prescribed in the FEMA P695 document.