Design of multi-array shaking table tests under uniform and non-uniform earthquake excitations

The feasibility of the shaking table test based on the multi-array shaking table system of Beijing University of Technology was verified by a self-designed rigid model box subjected to uniform and non-uniform excitations. The parameters of the shaking table and model box were elaborated, and the similarity ratio relationship was determined according to test conditions. The fundamental frequency tests of the empty model box and box-soil system were implemented, and observations were compared with numerical results. The boundary effect of the free-field shaking table test under uniform and non-uniform excitations was analyzed. The results showed that resonance could be avoided as a result of the fundamental frequency difference between the model box and model soil. The boundary effect could be avoided when the distance of observation objects from the model box boundary exceeds 0.25 m. Under uniform excitation, the response difference at the bottom of each box was less than 5%, which satisfied the requirements of uniform input. The time delay of seismic responses between two adjacent boxes was identical with expected values. Moreover, the spectral curves of the two active boxes were virtually the same under non-uniform excitation, satisfying the requirements of this excitation. The foregoing indicates that the model box was properly designed, and the shaking table test was feasible.