Large shaking table tests of pile-supported structures in different ground conditions

This study investigates the dynamic response of structures and the effect of soil-structure interaction for flexible structures supported by pile foundations located in non-liquefiable and liquefiable sites as well as a rigid foundation. A series of large-scale shaking table experiments were performed, and accelerations and dynamic displacements of model superstructures were recorded during the shaking events. It was observed that the structure in non-liquefiable soil deposits had the highest accelerations due to the amplification of ground motion within the soil. On the other hand, the accelerations of the structure in liquefied site was small due to the increased dissipation of seismic energy. The structures founded on soil experienced residual (permanent) lateral displacements, with the permanent lateral displacement and tilting of the structure in the liquefied site being much larger. The structure on rigid foundation (i.e. foundation on rock or fixed base) experienced high accelerations and oscillatory displacement as the seismic energy could not be dissipated. Therefore, structures in liquefiable soil are prone to overturning damage due to failure of their foundations. Furthermore, the base shear force of the structure in the non-liquefied site was significantly larger than that in the liquefied site and fixed-base, indicating it would be more susceptible to shear failure. On the other hand, the fixed-base structure experienced relatively large acceleration and dynamic displacement responses, which indicates increased seismic demands on its structural members.