Analytical Approach for Seismic Performance of Extended Pile-Shafts

Abstract

Seismic performance of bridge structures supported by extended pile-shafts principally depends on the curvature demand in critical regions of the pile below ground level. The equivalent fixed-based cantilever model is commonly used to assess the local curvature ductility demand of a yielding pile-shaft at any inelastic displacement level. In this approach, adequate prior knowledge of several parameters, including depth-of-fixity, plastic-hinge depth, and equivalent plastic-hinge length, is essential for proper estimation of ductility capacity. The present study aims to propose analytical formulations by using concepts of the strain wedge method based on nonlinear behavior of the soil-pile system to assess the key parameters of the equivalent cantilever model. The ability of the developed model in assessing the curvature ductility demand of the bridge system is validated against several published full-scale tests on RC shafts in clay and sand.