Evaluation of virtual fixed points in the response spectrum analysis of a pile-supported wharf

Response spectrum analysis is widely employed in the seismic design of pile-supported wharves, as it can easily determine the maximum response of a structure. The analysis typically uses virtual fixed points to model the structure, without modelling the ground, as the structure is assumed to be a frame. Virtual fixed points can adequately simulate pile responses under horizontal static loads; however, pile responses under seismic loads have not been well studied. Therefore, the dynamic centrifuge tests evaluate the applicability of response spectrum analysis, using virtual fixed points, to the seismic design of a pile-supported wharf. Comparison of results from scale models (3 × 3 groups of piles from sections of Pohang New Port, Korea) with those from the analysis showed that the response spectrum analysis using virtual fixed points does not adequately simulate the natural period or pile bending moment of a pile-supported wharf system.