Lateral Load-Deflection Relationships of Piles Subjected to Dynamic Loadings

Abstract

A simple representation of the dynamic lateral load-deflection relationship of a pile is presented for both pile-head and seismic excitation conditions. The lateral load-deflection relationship of a pile is represented by the soil reaction coefficient that is the ratio between a unit soil reaction on a pile and the product of soil modulus and pile displacement relative to the free field. As the soil reaction coefficient varies significantly along the pile even in a homogeneous soil, an averaging procedure is presented to determine an equivalent soil reaction coefficient that is constant with depth. The average soil reaction coefficients, δ˜, for homogeneous soil profiles are affected by the loading condition, pile flexibility factor, and pile slenderness ratio. The magnitudes of these influences are quantified. This averaging procedure can also be applied to heterogeneous layered soil profiles if a weighted soil modulus is used. The concept of the average soil reaction coefficient is extended to develop a procedure to compute the dynamic lateral load-deflection relations of piles when the stress-strain response of the soil is nonlinear and degrades due to pore pressure increases with cyclic loading.