Dynamic Soil-Structure Interaction of High-G Centrifuge Foundation

Centrifuge devices create bi-directional acceleration forces, resulting in rotational radial thrust, overturning moment and torsion which must be safely resisted by the foundation and surrounding earth materials. In addition, the vibration levels should not harm the machine operation nor adversely affect adjacent sensitive equipment. To achieve these objectives, detailed subsurface characterization together with 3-D dynamic soil-structure interaction using ABAQUS finite element program is implemented. The entire building which houses the centrifuge and surrounding area including the machine pit and foundation are incorporated into the analysis. The subsurface profile is discretized as having a clay overburden overlying shale bedrock. The dynamic soil/rock properties are obtained from field shear wave velocity measurements and laboratory testing. Modal extraction techniques are used to establish the system frequencies of vibration. The lowest two frequencies are then used to calculate the Rayleigh damping coefficients. In order to determine the vibration levels in other parts of the building, history nodes are incorporated into the model at key locations to save computer time and at the same time provide sufficient detail of the overall foundation response.