Performance-Based Seismic Response of Pile Foundations

Investigation of the correlation between so-called engineering demand parameters (EDPs) and various intensity measures (IMs) has received substantial attention in structural earthquake engineering, as accurate prediction of seismic demand is desired in performance-based seismic evaluation of structures. Little work however has been performed quantifying the seismic response of pile foundations within a performance-based context. In this study the seismic demands of pile foundations are investigated in a performance-based approach. A simple soil-pile-structure model consisting of a two layer soil deposit with a single pile and a single-degree of freedom superstructure is used in a parametric study to determine the salient features in the seismic response of the soil-pile foundation system. A suite of 40 `ordinary' ground motion records were scaled to various ranges of intensity to probabilistically investigate the full range of pile behaviour, from initial elastic response to failure. Various IMs are used to inspect their correlation with the seismic demand, which is measured in terms of: peak lateral displacement of the pile head (relative to pile toe) and peak pile curvature. The lowest scatter in the prediction of pile response was observed when seismic intensity was measured in terms of velocity-based IMs.