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

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.