Effects of Protective Cushion and Soil Compliancy on the Response of Equipment Within a Seismically Excited Building

Keywords: Nonstationary Random Processes, Component Mode Synthesis Technique, Modified Cascade Approach, Soil Structure Interaction, Linear Viscoelastic Cushioning Devices, Earthquake Resistant Design, Secondary Systems, Seismic Analysis, Primary Systems, Protective Cushioning, and Soil Compliancy.

Abstract: Protective cushion is shown to be effective for reducing seismically induced response of a piece of equipment, such as a computer, installed in a building. The cushioning device is assumed to be linearly viscoelastic in the analysis and the compliancy of the soil under the building is taken into consideration. The input earthquake excitation is modeled as a nonstationary random process. Since the building is generally a dynamic system of many degrees of freedom, approximate procedures are used in which only a limited number of important modes are included in calculating the equipment response. Guidelines for choosing such important modes are given, and the approximate results are compared with mathematically exact results in numerical examples.