Predicting Seismic Response of a Single Pile in Cement-Treated Soft Clay Using a Bouc-Wen Type Model

Seismic performance of piles in improved ground can be crucially affected by soil degradation, gap formation, and energy dissipation through material and radiation damping. In this paper, we investigated these mechanisms using centrifuge modeling of the response of a single pile to a seismic excitation. We represented the interaction forces between the pile and the soil system using discrete interaction elements distributed along the pile. The resisting force generated in each element consisted of a hysteretic component and a radiation damping component. The hysteretic force was formulated by the Extended Bouc-Wen (EBW) model and the key parameters of the model were calibrated. The simulated soil reactions were validated against their counterparts derived from the curve-fitted measured bending moments. The simulated soil reaction for the soft clay followed the trends and captured the peaks for most parts of the excitation. For the improved clay, however, the interaction element was unable to capture the significant hardening that occurred around the peak of the excitation. Contribution of the radiation damping in the simulated soft clay reaction was found to be much more significant than that of the improved soil.