Seismic analysis of pile in liquefiable soil and plastic hinge

Abstract

Liquefaction is one of the leading seismic actions that cause extensive damage to buildings and infrastructure during earthquakes. In many historic cases, plastic hinge formations in piles were observed at inexplicable locations. This project investigated the behaviour of piled foundations within soils susceptible to liquefaction by using numerical analysis carried out in Abaqus software in terms of plastic hinge development. Three different soil profiles were considered in this project that varied in the thickness of both the liquefiable and non-liquefiable layers, pile length and free- and fixed-head pile conditions. Modelling a single pile as a beam-column element carrying both axial and El Centro record earthquake loading produced results of the seismic behaviour of piles that could be assessed by force-based seismic design approaches. The displacements and deformations induced by dynamic loads were analysed for piles affected by liquefaction, and the results were used to demonstrate the pile capacity and discuss the damage patterns and location of plastic hinges. Parametric studies generally demonstrate that plastic hinge formation occurs at the boundaries of the liquefiable and non-liquefiable layers; however, the location can be affected by a variety of factors such as material properties, pile length and thickness of the liquefied soil layer.