An efficient static correction algorithm with application to the hydrodynamic loading of thin shell structures

An important class of design problems in the commercial nuclear power industry is concerned with the hydrodynamic loading of thin shell structures which form the boundary of a pool of water called the suppression pool. The purpose of the suppression pool is to condense high pressure steam released from the reactor pressure vessel during abnormal operating transients or postulated accident conditions. When these events occur, the steam condensation is preceded by the clearing of water and air under high pressure from within the piping connecting the pressure vessel to the suppression pool. The clearing of the water and air and the subsequent steam condensation produce transient pressure disturbances in the pool which are transmitted to the boundary. The response of the boundary structure, and its attached piping and equipment, to these loads is an important consideration in the design evaluation of the suppression pool system. This paper describes a solution to the problem of omitted structure modes by the introduction of a shape function which is specifically chosen to capture the quasi-static response of the structure. The shape function is appended to the set of dry-structure modes before the coupled system modes are computed. In this way the existing DMAP coding, developed for modal solution of fluid-structure interaction problems, can be used without alteration. The method can be thought of as a first-order application of the Ritz-vector technique. (orig./GL)