Possibilities and limitations of simplified methods for the seismic analysis of the HDR reactor building

Data from seismic tests at the HDR reactor building were used for a systematic evaluation of possibilities and limitations of 'simplified' seismic analysis methods. The models developed for this evaluation did not have more than 32 degrees of freedom. They were composed of two dimensional beams and lumped masses for the structure and of spring-dashpot elements for the soil. Eigenvalues, mode shapes and modal damping values of the soil-structure system were evaluated and compared with results from shaker tests. The structural response to an external blast excitation was analysed by the response spectrum method and compared with recorded data. It was found that a rather accurate determination of the basic structural behaviour is possible by using simple beam models with soil springs. Simplified analysis methods were confirmed to be powerful tools for the design or review of nuclear power plant structures, provided certain modelling criteria are observed. In particular they are well suited for parameter studies. (orig.)