Liquefaction induced displacement and rotation of structures with wide basements

Abstract

Earthquake induced liquefaction can cause structures with shallow foundations to experience large settlement and rotation, and can cause subsurface structures to uplift. The performance of structures with basements, which intuitively combine these two problems, is not understood. In this paper, data from three dynamic centrifuge tests on structures with wide basements are examined. The ratio of upward to downward vertical forces was varied, and a symmetric and asymmetric superstructure was tested. Digital image correlation was used to capture the soil displacements, providing novel insight into the co-seismic soil-structure interaction. The inclusion of wide basements was shown to reduce the overall settlement of structures by providing an increased uplift force during the liquefied period. For symmetric structures, symmetric soil displacements occurred around the basement during consecutive half-cycles of sinusoidal shaking, resulting in negligible accumulation of rotation. In contrast, significant rotation was accumulated for an asymmetric structure as a result of the P−δ effect due to the eccentric mass.