Boundary Effects for ESB Container in Dynamic Centrifuge Test Incorporating Numerical Simulation

The current study investigated the boundary effects induced by an Equivalent Shear Beam (ESB) container in a dynamic centrifuge test of a silica sand deposit. A fully nonlinear two-dimensional (2D) numerical model is established for the ESB container with soil by adopting nonlinear sand and hyperplastic rubber materials. A nonlinear frictional connection is adopted between the ESB and the soil. This study also proposes a numerical simulation procedure for ESB containers as boundaries for seismic analysis. A relationship between the fundamental frequency of the ESB container and rubber material properties is also proposed and provides a guide for the simulation of centrifuge tests with ESB containers. The established numerical model is validated via a dynamic centrifuge test. Investigation revealed that the boundary effects are minimal and are less than 20% at the base to the middle height of the soil deposits. The effects are significant on the surface and can reach 80% near the boundary. The effects remain less than 20% from the middle up to 0.3B (B: total width of soil deposit) toward the boundary. This position is recommended as the optimal location for sensor placement in centrifuge tests. It is also observed that the boundary effects are significant around the fundamental period of the soil deposit. The findings from the study provide a guideline for the numerical modeling of ESB containers and for determining the optimal location for sensor placement in centrifuge tests to minimize boundary effects.