近断层长周期地震动前向性效应对峰值影响研究

Study on Influence on Peak Value of Forward Directivity Effect for Near-fault Earthquake Ground Motions

筛选了断层距不大于15 km的具有前向性效应的长周期近断层地震记录,分类汇总建立了统计分析数据样本库,对长周期地震动的竖向分量和水平向分量峰值比进行了分析,研究了震级、脉冲周期、不同分量对峰值加速度比的影响。在此基础上,采用前期建立的回归分析模型,对长周期地震动竖向分量和水平向两个分量的峰值加速度进行了回归分析,拟合给出了峰值参数与震级和断层距的衰减关系式,通过拟合曲线与数据样本的峰值实测值对比,说明拟合关系式在一定的范围内可以用于近断层长周期地震峰值的预测。

Based on selected near- fault earthquake records characterized by forward directivity effect within 15km of fault projective distance, the long - period pulse near - fault ground motions database is constructed. The influence on the peak value acceleration ratios of vertical component and horizontal components by earthquake magnitude, pulse period and different component is analyzed. By means of the established regressed model, the attenuation relationships of the peak ground motion acceleration for the vertical component and horizontal components of near - fault long - period earthquake records are constructed. The main effect factors on the peak ground motions are discussed. The results show that the earthquake magnitude and fault distance have directly influence on the peak value. Comparing with the peak values of near - fault long - period ground motions records, we show that the regression curve can be used to the peak ground acceleration for structure located in near- fault zone.