| A fast algorithm of auto-PSD(Power Spectral Density)and cross-PSD for multi-excitation random seismic responses is suggested.This method naturally involves the cross-correlation items between the participant modes,as well as those between the excitations. It is shown that this is an efficient,simple and accurate algorithm within the frequency domain. In addition,the nonorthogo-nal damping matrix can be conveniently dealt with by using only structural real modes. |