Effects of Pile Tip Support Condition on Pile Behavior under the Action of a Large Earthquake

Abstract

Effective methods for evaluating the bending moment of a pile caused by lateral forces at the pile head are available. However, the effects of axial load variation caused by the overturning moment on pile responses have not been investigated in detail. To investigate the effects of pile settlement caused by axial load variations on the pile behavior under a large earthquake, dynamic centrifuge tests on soil–pile–superstructure models were performed. Centrifuge tests showed that the bending moment of the piles depended on the pile-tip support conditions. The test results were examined via numerical analyses using the monotonic beam on nonlinear Winkler foundation (BNWF) method. When the pile tips were supported by vertical springs and rollers, the bending moments at the pile head resulting from the overturning moment increased with the increase in the horizontal subgrade reaction in the subsurface soil. Our findings contribute toward rational seismic design of pile foundations under the action of a large earthquake.