Generation and analysis of spectrum-compatible earthquake time-histories using wavelets

A wavelet-based procedure is presented to generate artificial accelerograms compatible with a prescribed seismic design spectrum. The acceleration time-history of an actual earthquake is decomposed into a number of time histories using the continuous wavelet transform. Each component time history is then suitably scaled so that the response spectrum of the revised accelerogram matches the target spectrum. A new wavelet, based on the impulse response function of an underdamped oscillator, has been proposed for this purpose. A procedure to perform a baseline correction of the compatible accelerograms is also presented. The artificial accelerograms were analyzed in time and frequency using the wavelet transform and the Fourier transform, to examine how the spectral content of the signal evolves with time. An alternative way to match the design spectrum termed the "two-band matching procedure" is proposed with the objective of preserving the non-stationary characteristics of the original record in the modified accelerogram.