Evaluation of the Virtual Fixed-Point Method for Seismic Design of Pile-Supported Structures

Traditionally, in the codes for seismic performance evaluation of pile-supported structures (PSS), the piles are modeled using either a virtual fixed-point (VFP) method or a soil spring method, which can additionally simulate soil-pile interactions. The applicability and accuracy of the VFP method, which is originated from statically loaded piles, to evaluate piles under seismic loads has not been sufficiently explored, despite the popularity of the technique. Thus, this study evaluates the applicability of the VFP in the seismic design of PSS through pseudostatic and response spectrum analyses (RSA). Our results indicated that there was a significant difference in between the experimentally derived and VFP model-derived values for the natural period, acceleration, and moment response of the structure. This difference occurs because the soil-pile interaction is simulated through the fixed end in the VFP model.