Seismic Requalification of Pile-Supported Structure: Pseudo-Static Approach

Pseudo-static approaches often become handy due to their simplicity compared to the complex coupled continuum dynamic analysis and yield satisfactory results. A pseudo-static approach is employed herein to evaluate the response of a pile-supported structure located in a highly active seismic zone in northeast India. Pseudo-static approach essentially involves two main steps: estimation of maximum ground deformations and surface accelerations from a free field ground response study, combined with static analysis considering the surface acceleration and superstructure mass. In the present study, dynamic behavior of underlying soil strata was investigated using two high-quality element testing techniques—resonant column and dynamic simple shear tests. The dynamic soil properties were established and site-specific ground response study was conducted for the chosen site, using the artificially generated ground motions for the region. Equivalent static load was estimated from the surface acceleration obtained from free field ground response study. A three-dimensional finite element model has been developed and validated against the field lateral load test results. An increased magnitude of displacement and bending moment was observed with increased ground motion intensity. The peak bending moments induced for the scenario ground motions is higher than the plastic moment capacity of the pile section, displaying the probable failure of considered pile-supported structure.