Spectrum matching of recorded ground motions with improved velocity and displacement time histories in frequency space.

摘要

A suite of ground motions are required for nonlinear dynamic analysis of the structures that are not categorized in simplified standard structural model. Typically, due to a lack of enough recorded ground motions with the desired magnitude-distance-site conditions in the region of study, recorded ground motions from other locations must be used. The records have to be adjusted to fit a code-required target spectrum. In this study, a new spectrum matching method in the frequency domain is proposed that retains more of the original record's time characteristics. Because single-factor scaling of motion is integrated in the technique, the adjusted ground motion has better correlation with the original ground motion than those matched using existing methods.;Existing spectral matching techniques in the frequency domain distort the displacement time history of the ground motions. This study shows that the velocity value at the end of the record is not affected by Fourier amplitude spectrum scaling but the displacement may linearly increase (or decrease) boundlessly. Two numerical solutions are proposed to solve the displacement drift problem in the frequency domain. Following the proposed frequency domain base-line correction procedure, one does not need to perform a base-line correction in the time domain after completing the spectral matching. As a result, acceleration, velocity, and displacement time histories will remain fully compatible and the boundary conditions of the velocity and displacement time histories will be preserved. The proposed procedure is not limited to spectrum matching methods and can be used with any general filtering process to retain the final displacement of the record.;The possibility of applying a zero-padding technique to the spectral matching filter is also discussed. It is shown that applying an appropriate window along with the zero-padding technique can lead to a reasonable displacement time history. The proposed procedures can be easily added to existing or new frequency domain spectral matching algorithms without significantly disrupting the spectral matching process.