波动-谱比法获取地震动转动分量研究

Study on obtaining rotational component of ground motion using wave-spectral ratio method

为从地震动平动记录中获取转动分量,提出了一种综合波动理论和谱比分析的新计算方法,即波动-谱比法.采用波动理论推算地震动转动分量的频域解,当P波和SV波均存在时,采用谱比法获得二者的比例系数,进而获取时域内的转动分量.该方法克服了P和SV波同时存在时直接利用弹性波动理论无法计算的关键问题,修正了利用谱比分析获取的转动分量时缺乏地震波高频分量的缺陷,能完整得到全频域范围内的转动分量.对具有典型转动倾斜特征的Northridge地震记录进行分析后,利用本方法由平动记录获取了全频域范围内的转动分量,计算结果与记录数据符合较好,验证了方法的可靠性及准确性.

To obtain the rotational component from the translational component of ground motion,a new method combining the elastic wave theory and spectral ratio analysis was proposed.The elastic wave theory method was applied to obtain the frequency domain solution of the rotational component of ground motion,and the ratio coefficient was obtained by spectral ratio method when P and SV incident waves appeared at the same time,so as to obtain the rotational component in the time domain.The proposed method not only overcome the shortage that the elastic wave theory cannot calculate the rotational component when P and SV incident waves appear at the same time,but also improve problem in the calculation of using the spectral ratio analysis with missing high frequency part of seismic wave,and the rotation components in the whole frequency domain can be obtained completely.After analyzing the Northridge seismic records with typical rotational tilting characteristics,the rotation components in the whole frequency domain were obtained from the translational records using the proposed method,and the calculation results were consistent with the recorded data,verifying the reliability and accuracy of the method.