Critical Soil-Structure Interaction Analysis Considerations for Seismic Qualification of Safety Equipment

While developing seismic analysis models for buildings that support safety-related equipment, a number of issues should be considered to ensure that the input motions for performing seismic qualification of safety-related equipment are properly defined. These considerations are listed and discussed here with special attention to the effect and importance of the interaction among the foundation soil, the building structure, the equipment anchors, and the equipment structure. Typical industry practices are critically examined to assess their adequacy for determining the input motions for equipment seismic qualification. The features that are considered essential in a soil-structure interaction (SSI) model are described. Also, the effects of inappropriate treatment or representation of these features are discussed.