Abstract:During earthquakes, piles undergo stresses due to both the motion of the superstructure(inertial interaction)and that of the surrounding soil (kinematic interaction).Based on the artificial viscoelastic boundary, a 3D numerical model of seismic performance for superstructure-pile-soil interaction was developed to analyze the kinematic response of PHC pile (prestressed high concrete pipe pile) during earthquakes.The kinematic seismic interaction of single piles embedded in soil was evaluated by focusing on the bending moments induced by the transient motion.Considering the conditions of layered soil, factors influencing the analysis included PHC pile diameter, the ratio of shear wave velocities between two soil layers, the depth of embedded soil, and the inertial loading of the superstructure.The results indicated that pile diameter affects the amplitude of bending moments at the pile head.Specifically, at the interface between layers for a given soil deposit, the bending moment increased as the pile diameter increased, especially at the interface of two soil layers.In soil profiles where the transition between layers was distinct, the bending moments in the pile were significant, especially near the interface of soil layers with highly contrasting stiffness.The bending moment at the interface between two soil layers of soil increased when the ratio of shear wave velocities increased.An increase in the depth of overlying soil in two soil layers would also cause an increase in the pile bending moment at the interface between the two layers.The fixed head of a pile and the interface of two soil layers would increase the bending moment.The superstructure had an important influence on the bending moment of the pile head, but not for the deep section of the pile.The conclusions of this study will lead to recommended reference criteria for the seismic design PHC piles
