Influence of Domain Boundaries on the Response of Isolated Structures on Liquefiable Soils

Geotechnical centrifuge modeling is a common tool that provides insight into the liquefaction phenomena and its associated consequences on buildings. Most prior experiments that aimed to evaluate an isolated structure's response had one or more model buildings present in the container at a center-to-center spacing ranging from about 2W to 4.6W (where W is the foundation width). This paper presents the results of two centrifuge experiments to evaluate the influence of container boundaries and possible interaction with other building models in a flexible-shear-beam (FSB) container. The first test involved one structure in the center of the container with no other buildings present. The second test included two similar structural models inside the container with a spacing of 3.5W. In parallel, fully-coupled, 3D, nonlinear numerical simulations of the same soil profile and structures were performed in OpenSees with two structures at different spacings and with different domain sizes. The structures represented the key dynamic properties of a prototype 3-story, potentially inelastic, multi-degree-of-freedom (MDOF) building on a mat foundation. The experimental and numerical results indicate that the presence of another structure can have a substantial influence on the building's permanent settlement and rotation even with a separation distance exceeding 3.5W. In the numerical analyses, a smaller domain size was observed to reduce foundation settlements by up to 18%. The important influence of interaction with container boundaries and other model structures needs to be considered in the design of centrifuge experiments that are used in model validation related to soil liquefaction and its consequences.