Evaluation of Seismic Demand of Pile Foundation for Performance Based Design

Accurate prediction of seismic performance of structures is important in reducing risks from earthquakes. Within the context of emerging performance-based earthquake engineering trends, seismic performance is measured with respect to the demand of engineering systems during a seismic event as opposed to the conventional factor of safety approach. Investigation of the correlation between so-called engineering demand parameters and various intensity measures has received substantial attention in earthquake engineering, as accurate prediction of seismic demand is desired in performance based seismic design. In this study the seismic demand of pile foundations are investigated in a performance based approach. A soil-pile-superstructure model consisting of group piles and superstructure is used in a parametric study to determine the features in the seismic response of the pile foundation. A dynamic time-step analysis is used in this research because of accurate prediction of the seismic response and estimation of the inelastic response. The seismic demand on a pile is generally related to the hysteretic energy released due to inelastic behaviors during ground shaking, so with respect to energy dissipation, various intensity measured are used to inspect their correlation with the seismic demand, which is measured in term of damage index. We use a suite of ground motion records scaled to various ranges of intensity to probabilistically investigate the full range of pile behavior from initial elastic response to failure