近场长周期强地震动幅值谱研究

STUDY OF LONG PERIOD STRONG MOTION AMPLITUDE SPECTRA IN NEAR FIELD

本文研究了近场长周期强地震动加速度的傅氏谱和功率谱模型及其参数估计方法,基于强地震动参数统计上的无向性,提出了一种结合地震学模拟模型和工程学统计回归模型的综合方法。文中定义了强地震动平稳段均方根加速度的计算方法,并通过均方根加速度建立了震源力学参数和强地震动工程参数间的关系。通过对目前使用的主观持时定义的应用分析,指出主观持时定义使得估计的地震动过程的峰值加速度的变异性与实际地震动过程的峰值加速度的变异性有显著不同,明显偏小,这对于结构抗震可靠度分析可能会得到失效概度偏小的结果,应引起工程界的重视。

Long period Fourier amplitude spectra and power spectrum of strong motion acceleration in near field have been discussed. Based on the non-directional character on statistice for strong seismic motion parameters, a hybrid method combining dynamic simulation model on seismology with statistical regression models on earthquake engineering has been presented. The stationary stage root-mean- square acceleration of strong motion is also defined, and the relationship between earthquake source dynamics parameters and seismic motion statistical papameters is set up through the root- mean-square acceleration. By pratical examples analysis for the present subjective duration, we find that the variability of peak acceleration of estimated strong motion stationary process defined by the stationary duration is apparently smaller than the one of peak acceleration of strong motion records, it may result in that the calculation probability of failure of structures is smaller than the real value in aseismic reliability analysis of structures, it is valuable to pay attention by engineers.