COMPARISON OF APPROXIMATE METHODS FOR SLIDING AND ROCKING EVALUATION OF UNANCHORED PLATFORMS

摘要

There are many unanchored structures in use in commercial nuclear power plants. Most widely used are scaffolding frames in support of plant outages. In general, unanchored structures are not safety related and are of no safety concern unless Seismic Category 1 SSCs (Structures, Systems, or Components) are present in their zone of influence. For such situations, the stability of the unanchored bodies under a seismic event must be checked to ensure that adverse interaction between the source (the unanchored structure) and safety related targets, does not occur. This phenomenon is commonly referred to as "Seismic II over I" interaction, "Seismic separation" or "Zone of influence" interaction. The issues of concern for seismic stability of an unanchored body are the extent that it could slide, as well as the maximum angle of rotation associated with rocking of the body and potential for tip-over (i.e., instability).