速度脉冲地震下偏心剪力墙结构的抗震需求

Seismic demand for eccentric wall structures subjected to pulse-like ground motions

研究强速度脉冲地震作用下,刚度偏心、强度偏心和组合偏心剪力墙结构的弹性和弹塑性抗震需求。基于轴力-弯矩相互作用模型,选取8条速度脉冲地震记录,进行单层钢筋混凝土(RC)偏心剪力墙结构的动力时程分析,讨论结构的弹性位移和扭转角需求,弹塑性位移、扭转角和延性需求的变化规律,揭示不同偏心形式对结构抗震需求的影响机理。研究结果表明:偏心剪力墙结构在强速度脉冲工况下比在非速度脉冲工况下有更大的抗震需求;轴压比对结构弹塑性抗震需求有一定影响;刚度偏心是影响结构弹性抗震需求的主要因素,而强度偏心对结构弹塑性抗震需求的影响最为显著。建议对偏心剪力墙结构进行弹塑性分析时宜增加强度偏心作为基本参数,并考虑轴力影响和速度脉冲地震效应。

The elastic and elasto-plastic seismic demands for shear wall structures, with stiffness, strength and combined- stiffness-and-strength eccentricity, subjected to velocity pulse-like ground motions, were investigated. Based on the axial load-bending moment interaction model and eight pulse-like ground motions, nonlinear dynamic time history analysis was conducted to single reinforced concrete （RC） eccentric wall structures. The elastic seismic demand was discussed in terms of displacement and rotation, while the elasto-plastic seismic demand was discussed in terms of displacement, rotation and ductility. The influential mechanism of different eccentricities was also revealed. The results show that the eccentric systems experience much higher seismic demand under pulse-like cases compared to non-pulse-like cases. The axial compression ratio has certain effect on the elasto-plastic seismic demand. The stiffness eccentricity is a main factor for elastic response, while the strength eccentricity influences the elasto-plastic response most. The strength eccentricity is suggested to be added as a basic parameter in the elasto-plastic analysis of eccentric wall structures, and the influence of axial load as well as earthquake velocity pulse-like effect are also taken into account.