Ductile Seismic Performance Analysis of Bridge Pile-group Foundations in Sand

Abstract:

In this paper， the rigorous incremental dynamic analysis （IDA） method is employed to systematically investigate the ductile seismic performance of pile-group foundations （PGFs）. A shake-table test on the pier-PGF system in sand is firstly used to validate the numerical modelling technique. Based on the engineering practice， a series of analytical models are then established considering the variation of nine structural/geotechnical parameters. Seven ground motion records are selected for the implementation of IDA. Finally， the seismic failure process of PGFs is validated and three performance indicators in terms of displacement， rotation and strength are proposed. And the impact of each parameter on the proposed performance index is investigated. It is found that for PGFs in the easy-to-repair state， the average displacement ductility is 2.52 and the average lateral strength is 1.41 times of that of the first-yield state. The average ultimate displacement ductility of PGFs is 3.62 and the average ultimate lateral strength is 1.47 times of that of the first-yield state. The maximum drift ratio of the pier induced by pile-cap rotation is less than 0.7%.