弹塑性SDOF体系地震输入归一化等效速度谱

为了确定弹塑性单自由度( single degree of freedom, SDOF)体系地震输入能,分析了中美场地土剪切波速转换关系,将从美国PEER地震记录数据库选取的220条强震记录按中国场地土类型进行分类,基于能量平衡原理,采用归一化方法,建议了一种基于复合强度指标的弹性SDOF体系三段式等效速度谱。分析了5类场地土条件下SDOF体系系统参数对地震输入等效速度谱的影响。研究结果表明：刚度折减系数对等效速度谱无明显影响；延性系数和阻尼比增大均对等效速度谱峰值和下降段衰减速度有削弱作用。综合考虑各类影响因素,通过参数多次拟合,得出弹性SDOF体系归一化等效速度谱峰值段及下降段修正系数,提出了一种适用于我国场地土类型、可直接供设计使用的弹塑性SDOF体系归一化等效速度谱确定方法,并验证了其有效性。

Earthquake Input Normalized Equivalent Velocity Spectrum for Inelastic SDOF Systems

Based on the relationship of shear wave velocity between the United States and China, 220 seismic records were selected from American PEER database and classified according to Chinese site classification. With the normalized method, the equivalent velocity spectrum of elastic signle degree of freedom ( SDOF) systems was simplified into three portions based on a complex intensity index. The influence of the SDOF system parameters on the earthquake input equivalent velocity spectrum for five types of site soil was analyzed. The results show that the stiffness deduction coefficient has no effect on the equivalent velocity spectrum, and the peak and the declining stage of the equivalent velocity spectrum decrease with the increase of ductility coefficient and damping ratio, respectively. With the multiple fitting methods, the modified coefficients for the peak and the declining stage of the normalized equivalent velocity spectrum for elastic SDOF systems were proposed by considering all influence factors. Finally, the normalized equivalent velocity spectrum for inelastic SDOF systems was suggested, and the effectiveness was verified. This method can be applied to Chinese site soil and is also convenient.