Study of the seismic response of a nuclear powerplant building

The primary aim of the present series of computational studies is to observe the seismic response of a nuclear power plant (NPP) control building under various earthquake scenarios in the Finnish geological context. These scenarios are the Design Basis Earthquake (DBE) and the Design Extension Earthquake (DEE) as prescribed by the Finnish YVL guides. In addition to these normative earthquakes, it has been considered appropriate to investigate earthquake ground motions of the type likely to be experienced at the location of interest. These are called the Natural Design Basis Earthquake (NDBE) and the Natural Design Extension Earthquake (NDEE) in the report. Other aspects of the study includes a comparison between a linear modal dynamics analysis and a non-linear explicit time integration analysis. In seismic design, the modal dynamics analysis on a viscously damped linear elastic structure is the baseline analysis strategy. The use of non-linear material models in seismic analysis of structures have not yet been approved unanimously by the engineering trade, which motivates this comparative study between the two modelling paradigms on a full-scale nuclear structure. Further, a comparison between different ways to model the ground layer under the nuclear structure is reported: using a node based linear spring versus using a continuum description. Together, these comparative studies are expected to increase the level of knowledge in the field of seismic structural engineering and analysis in the nuclear context.