An ameliorative duration of pulse-like ground motion records for nonlinear structural analysis

Abstract

The near-field pulse-like ground motion contains obvious long-period and large pulse characteristic, which makes the nonlinear response of the structure exceed the general prediction of seismic response results. In order to reserve the obvious pulse component while selecting the strong ground motion duration part of the near-field pulse-like ground motion record without causing a large loss of spectral characteristics, the paper proposes an ameliorative truncated strong ground motion duration—useful duration. It is proposed based on the elastic acceleration response spectrum. Its principle is to make the acceleration response spectrum corresponding to useful duration and that corresponding to the original ground motion record as close and consistent as possible. The research results show that from the perspective of elastic response spectrum matching, the response spectrum matching error corresponding to useful duration is smaller than that of significant duration. In addition, the five types of periods corresponding to useful duration are closer to the period of original ground motion. Ulteriorly, from the displacement ratio spectrum of the elasto-plastic single-degree-of-freedom system, it is found that the average value of the elasto-plastic displacement ratio spectrum of useful duration and the original ground motion record is 0.98, which is very close to 1.00. It shows that the truncated ground motion can be used to replace the original ground motion to fully predict the nonlinear response of typical structures. Additionally, the effectiveness is further verified in the nonlinear response of three reinforced concrete frame structures, and the nonlinear response results of the structures are calculated using the time-history of useful duration, with less discreteness.