Wavelet analysis for relating soil amplification and liquefaction effects with seismic performance of precast structures

Abstract

Summary Precast concrete structures are preferred for facilities with large open areas due to easiness in construction. Such structures are typically composed of individual columns and long‐span beams, and are quite flexible and of limited redundancy. In this paper, nonlinear dynamic analyses of a typical such structure are conducted using as excitation 54 ground motions recorded on top of a variety of soils (hard, soft, and liquefied soil sites). The results show that liquefaction‐affected level‐ground motions systematically impose a greater threat to precast‐concrete structures in terms of seismic demand, even when low values of elastic spectral acceleration prevail, as opposed to soft‐soil records and even more to hard‐soil ones. Thus, elastic spectral acceleration appears to be an insufficient engineering demand parameter for design. Soil effects, the “signature” of which is born on ground motions, are first uncovered using wavelet analysis to detect the evolution of the energy and frequency content of the ground motion in the time domain. From this, the changes in effective (“dominant”) excitation period are noted, persuasively attributed to the nature of the soil, and finally correlated with the observed structural behavior. Copyright © 2016 John Wiley & Sons, Ltd.

Special Issue: Resilience and Sustainability of Civil Infrastructures under Extreme Loads

“…For example, seismic excitations usually contain multiple frequency components, and therefore the plastic deformation of the structure continuously accumulates in a certain direction, resulting in a large nonlinear displacement [1,2]. Moreover, liquefaction may occur after earthquakes, as it is worth mentioning that liquefaction can cause seismic settlement and tilting of structures [3,4]. Even worse, the progressive collapse of buildings is more likely to happen if structural redundancy suddenly decreases because of unexpected abnormal loads [5,6].…”