拟合核电厂多维设计反应谱及相关峰值的地震动调整方法

A method of modifying earthquake ground motion for matching multi-dimensional nuclear power plant design response spectra and peak values

依据核电厂结构的特殊性,提出了一种以核电厂多维设计用伪加速度反应谱及峰值加速度(PGA)、峰值速度(PGV)、峰值位移(PGD)为目标的实际地震动调整方法。该方法首先应用二阶基数B-样条小波函数模拟实际多维地震动场,然后基于离散小波变换的快速算法,将实际地震动加速度时程应用二阶基数B-样条小波函数进行分解;一方面探寻对各向分量的PGA、PGV及PGD影响最大的小波分量,另一方面通过对小波系数进行初步调整以改进时域叠加小波函数的收敛性;最后通过循环调整实现对多维目标反应谱及PGA、PGV、PGD的同时拟合。选取了四组代表不同设计地震分组的三维实际地震记录分析了该方法的可行性,结果表明:该方法不仅较好的保留了原地震动的局部时频特性,且能满足核电厂抗震设计规范的精度要求。

According to the specificity of nuclear power plant structures, a method of modifying earthquake ground motion was proposed for matching multi-dimensional nuclear power plant design response spectra and peak values of ground acceleration （PGA）, ground velocity （PGV） and ground displacement （PGD）. Firstly, the second cardinal B- spline wavelet was used to simulate multi-dimensional earthquake ground motion. Then, real earthquake records were decomposed into several wavelet components with the fast algorithms of discrete wavelet transformation. On the one hand, the wavelet components affecting PGA, PGV and PGD of each direction could be searched out; on the other hand, the convergence of the synthesis wavelet method could be improved with the preliminary modification of wavelet coefficients. Through iterations, the multi-dimensional target response spectra and PGA, PGV and PGD could be matched simultaneously. Four groups of three-dimensional real records representing different earthquake groups were used to verify the feasibility of the proposed method. The results of numerical examples demonstrated that the method can not only retain the local time-frequency features of the real earthquake records, but also satisfy the precision demand of the codes for a seismic design of nuclear power plants.