Equivalent Plastic Hinge Length of Extended Pile-Shafts embedded in Sand

Under strong seismic excitation, the extended pile-shaft will inevitably form a plastic hinge in its underground portion. The underground damage is difficult for post-earthquake restoration and may cause large residual displacement at the top of the pile-shaft. In this regard, the ductile behavior, especially the characterization of the underground plastic hinge needs to be investigated. In this paper, a Beam on Nonlinear Winkler Foundation (BNWF)-based finite element (FE) model embedded in a homogeneous sand layer was developed in the Open Sees platform and calibrated by an in-situ full-scale test. This study focused on the effect of different structural and soil parameters on the equivalent plastic hinge lengths(EPHLs) of extended pile-shafts. Results indicate that the EPHLs of piles are affected by many parameters of pile-soil systems. A typical range of EPHLs of the pile is also obtained from the parametric study.