地震动加速度反应谱场地条件影响调整系数研究

Study on Scaling Ratios for Spectral Accelerations of Ground Motion Due to Site Conditions

场地条件对地震动特性影响显著,在抗震设计反应谱的确定过程中,需根据场地条件对加速度反应谱予以相应的调整。已有场地条件影响调整方案研究成果,均基于数值模拟或局部地区强震动记录统计,多数仅给出了峰值加速度PGA场地条件影响调整系数,对非线性的考虑缺乏观测数据依据。为此在全球强震动记录统计获得的PGA归一化加速度反应谱和日本钻井台阵记录获得的加速度反应谱平台值非线性衰减指数的基础上,结合钻孔模型数值模拟和近期研究成果,建立了考虑场地条件影响非线性的地震动加速度反应谱场地条件影响调整系数方案。

The characteristics of ground motion are significantly affected by site conditions. During the determination of seismic design spectra, it is necessary to adjust the spectral accelerations according to the site conditions. Most of the current adjustment schemes only gave the peak acceleration(PGA) scaling ratios lacking of observing basis for considering the nonlinearity, which were based on numerical simulations of borehole models or statistics of local strong motion records. Based on the PGA normalized spectral accelerations obtained from the statistics of global strong motion records and the nonlinear attenuation exponents for platform values of spectral accelerations obtained from the records of Japanese borehole arrays, combined with the numerical simulation of borehole models and the previous research results, a novel scaling ratios for spectral accelerations of ground motion due to site conditions considering the nonlinearity is established in this paper.