地震波斜入射输入体系下坝后式厂房易损性分析

为了考虑地震波斜入射对坝后式厂房易损性的影响，通过斜入射SV波和P波波场叠加，在地表得到与实测地震动一致的设计地震动分量。同时为了考虑坝后式厂房的动力损伤，在程序中嵌入混凝土动力损伤本构，编写了可以考虑地震波斜入射体系的结构易损性分析程序。最后从太平洋地震工程研究中心（PEER）数据库中选取26条近场地震动数据，根据峰值地面加速度（PGA）对每条地震波进行调幅，以我国西南地区某坝后式厂房为工程实例，用增量动力学分析法计算了其上下游墙体在不同强度斜入射体系地震动作用下的易损性曲线。与传统垂直入射模式下的地震易损性曲线对比发现，传统垂直入射下的破坏概率较高，两种入射模式破坏概率最大相差26%。其中，坝后式厂房下游墙的破坏概率比上游墙大，最大相差可19%。因此坝后式厂房的抗震设计需考虑地震波斜入射的影响，并重点考虑下游墙部位的抗震安全性。

Vulnerability analysis of a powerhouse at dam toe under the input of obliquely incident seismic waves

To study the influence of obliquely incident seismic waves on the vulnerability of powerhouse at dam toe, the design seismic component consistent with measured ground motion was first obtained on the surface through the superposition of obliquely incident SV-wave field and P-wave field. Meanwhile, in order to consider the dynamic damage of the powerhouse, a program of structural vulnerability analysis considering the system of obliquely incident waves was compiled, in which a damage constitutive model of concrete was embedded. Finally, 26 near-field ground motions were selected from the PEER database and modulated according to the peak ground acceleration (PGA). Taking a powerhouse at dam toe in southwest China as an example, the vulnerability curves of its upstream and downstream walls under the action of obliquely incident system with different intensities were calculated with the incremental dynamic analysis method. Through comparison, it is found that the failure probability of seismic vulnerability curves under vertically incident waves is relatively higher than that under obliquely incident waves, with the maximum difference of 26%. The failure probability of downstream wall is higher than that of upstream wall, and the maximum difference is up to 19%. Thus, the seismic design of powerhouse at dam toe should consider the effect of obliquely incident seismic wave, and more attention should be paid to the seismic safety of downstream wall.