Wavelet-based generation of accelerogram-consistent, spectrum-compatible motions: New algorithms and short-period overestimation

• Published in: Soil dynamics and earthquake engineering (1984) Vol. 121; pp. 327 - 340
• Main Authors: Mukhopadhyay, Suparno, Das, Sandip, Gupta, Vinay K.
• Format: Journal Article
• Language: English
• Published: Barking Elsevier Ltd 01.06.2019; Elsevier BV
• Subjects: Acceleration; Algorithms; Compatibility; Computer simulation; Earthquake accelerograms; Fourier spectrum; Matching; Nonstationarity; Optimization; Seismic design; Short-period overestimation; Spectrum-compatible ground motion; Wavelet; Wavelet analysis; WAVGEN; Nonstationarity; Wavelet; Fourier spectrum; Spectrum-compatible ground motion; WAVGEN; Short-period overestimation
• ISSN: 0267-7261; 1879-341X
• DOI: 10.1016/j.soildyn.2019.02.001

The use of spectrum-compatible accelerograms in seismic design of structures has lately become popular and several algorithms have been proposed to generate such accelerograms. Some of those algorithms can be used to generate accelerogram-consistent motions, i.e., the motions in which the nonstationary features of a given seed motion are replicated. In a popular algorithm of this type a recorded motion is modified via frequency-band-dependent modification factors such that it becomes compatible with a target spectrum and the nonstationary features of the original motion are preserved in the component narrow-band wave levels of the modified motion. In the present paper, the performance of this method is critically reviewed in terms of convergence rate, degree of modification of the seed motion and the quality of matching in the zero-period acceleration (ZPA) region of the target spectrum. It is observed that the first two issues can be addressed by properly taking into account the pseudo-static response of an oscillator due to a narrow-band excitation. Two new algorithms are therefore proposed, one works by computing the modification factors sequentially and the other one simultaneously. An improved matching is also attempted in the ZPA region by using a direct constrained optimization. Further, additional insight is provided with the help of numerical examples to determine whether the given combination of target spectrum and seed motion may lead to a short-period overestimation in the simulated motion. •Three new algorithms proposed for simulation of spectrum-compatible accelerograms.•Algorithms based on modifying the contributions of component waves of seed motion.•Modification factors based on sequential, simultaneous and optimized determinations.•Indicator developed to detect the possibility of PSA overestimation at short periods.