Effects of Structural Material Damping on Nonlinear Seismic Response of Offshore Piles

Nonlinear response of pile foundations is the most important part of potential nonlinear response of pile supported offshore platforms to seismic excitations. Soil nonlinearity, soil radiation damping and structural material damping are the main sources of energy dissipation in seismic behavior of offshore piles. In this study, a practical BNWF (Beam on Nonlinear Winkler foundation) model is used to compute the nonlinear lateral response of piles, embedded in layered soil deposits, subjected to seismic loading. The results of equivalent linear and nonlinear earthquake free field ground motion analyses are used as the input excitations at support nodes of the model. Sensitivity of the pile seismic responses to structural material damping ratios are discussed and addressed in this paper. Numerical results are compared with centrifuge test results.