Dynamic analysis for laterally loaded piles and dynamic p-y curves

Pile foundations are often subjected to lateral dynamic loading due to forc es on the supported structure. In this study, a simple two-dimensional anal ysis was developed to accurately model the pile response to dynamic loads. The proposed model incorporates the static p-y curve approach (where p is t he static soil reaction and y is the pile deflection) and the plane strain assumptions to represent the soil reactions within the frame of a Winkler m odel. The p-y curves are used to relate pile deflections to the nonlinear s oil reactions. Wave propagation and energy dissipation are also accounted f or along with discontinuity conditions at the pile-soil interface. The incl usion of damping with the static unit transfer curves results in increased soil resistance, thus producing "dynamic p-y curves." The dynamic p-y curve s are a function of the static p-y curve and velocity of the soil particles at a given depth and frequency of loading. The proposed model was used to analyze the pile response to the lateral Statnamic load test, and the predi cted response compared well with the measured response. Closed-form solutio ns for dynamic p-y curves were established by curve fitting the dynamic soi l reactions for a range of soil types and loading frequencies. These soluti ons can be used to model soil reactions for pile vibration problems in read ily available finite element analysis (FEA) and dynamic structural analysis packages. A simple spring and dashpot model was also proposed to be used i n equivalent linear analyses of transient pile response. The proposed model s were incorporated into an FEA program (ANSYS) which was used to compute t he response of a laterally loaded pile. The computed responses compared wel l with the predictions of the two-dimensional analysis.