Accuracy of dynamic calculations using shell models under local impulse loading

Depending on soil conditions and load cases in dynamic calculations of nuclear power plants today more exact mathematical models may be used. For axisymmetric structures like reactor buildings, steel containments, circular tanks or coolant towers mathematical idealisations are used which especially deal with axisymmetric shell models. The calculations for these structures mentioned above, in the last 10 years, were generally carried out by applying specialised and qualified FE-programs. In order to qualify the results obtained using axisymmetric shell models as well the approved computer program MESY (Schrader 1976, 1978) several comparisons between computation and measurements were performed. As an example for these comparisons, impulse loadings, such as aircraft impact, applied by means of a pendulum on the HDR reactor will be shown. The analytical results were obtained prior to the general tests based on a loading function measured in a preliminary test step. In these calculations 11 harmonics were considered in the frequency range up to 80 Hz. Typical results will be shown and discussed, particularly the distribution of the maximum acceleration in the meridional and circumferential direction of the building. The analytical results for the structural response obtained using axisymmetric shell models conform satisfactorily to test results, especially in the area of load introduction in both (meridian and circumferential) directions. (orig.)