Pseudo-Dynamic Test for Soil-Structure Interaction Analysis using Shake Tables

This paper presents an effective pseudo-dynamic (PSD) test method for analyzing the response of a multi degree of freedom structural system. In addition to the physical and numerical substructuring of the structure, the effect of the soil-structure interaction (SSI) is numerically modeled without a large soil box. The governing equation is separated into those for the superstructure and the base. These are coupled equations that can be solved recursively with the prediction of the superstructure acceleration, for which polynomial extrapolation is employed. The input for the structure is then obtained by solving the coupled equilibrium equations for experimental and analytically modeled systems. The restoring force applied underneath the superstructure is measured and used to update the superstructure acceleration. The stability condition for the proposed method is investigated, revealing a longer range of the convergence criterion than the Newmark explicit method. The implicit feature of the proposed method enables PSD tests irrespective of the modal properties, if the sampling frequency condition is satisfied. Additionally, the amplitude decay and period elongation are investigated for accuracy comparison in the structural responses. A series of PSD tests are performed using a two degree of freedom shear-building model to validate the proposed method. The experiment is performed on one part of the physical structure, while a numerical simulation is performed on the other part of the structure and on the SSI. The test results confirm that the proposed PSD algorithm is reliable for simulating the substructure and SSI effect.