A new algorithm to generate spectrum-matched ground motions at single and multiple sites considering spatially varying characteristics

Spectrum-matched records are widely used in structural design and antiseismic evaluation. The available approaches in the literature are based on only one of the following transforms: the Fourier transform (FT), continuous Wavelet transform, or S-Transform (ST), and are mostly designed for spectrum matching at single sites. The present study first reviewed the FT and ST and explained the interrelation between them. Then, by using the connection between FT and ST, and adopting the concept of synchronized phase shuffle used in the Iterative Power and Amplitude Correction (IPAC) algorithm for multiple sites, two spectrum matching algorithms are proposed: one for spectrum matching at single sites, denoted as RSM-Single, and one for spectrum matching at multiple sites, denoted as RSM-Multi. The RSM-Single is shown to be efficient as compared to the only ST-based approach, in matching a prescribed response spectrum at specified frequencies, and retaining the look of the acceleration time histories of the seed records. The RSM-Multi could be used for generating seismic ground motions across multiple sites while matching the target design spectrum and retaining the coherence structure. The seed record selected in this case served to initiate the RSM-Multi algorithm, provide a more realistic look, and transfer their characteristics to the spectrum-matched records. Examples were given to show the ability of the proposed algorithms. Finally, a comparison of the structural response of a latticed shell subjected to spectrum-matched records with and without including the incoherent effect is given and indicates the importance of considering spatially varying characteristics in generating the spectrum-matching records for multiple sites.