NONLINEAR SEISMIC ANALYSIS OF AN IN-PLANT PIPING SYSTEM

Dynamic tests with simulated earthquake excitation were performed during April-May ۱۹۸۸ on the VKL piping system at the HDR Test Facility in Kahl/Main, Federal republic of Germany. One of the objectives of the tests was to evaluate analytical methods for calculating the nonlinear response of realistic piping systems subjected to high-level seismic excitation that would induce either failure or significant plastic deformation in the pipe runs. The calculations were performed for a reasonably compliant piping system with only rigid struts for dynamic supports. The nonlinear finite element code NONPIPE was used to calculate responses for ۸۰۰% safe-shutdown earthquake loading. The NONPIPE code computational estimates were evaluated by comparing them with measurements from the test that caused significant nonlinear response and plastic deformation,The response calculated with NONPIPE were found generally to have the same time trends as the measurements but contained under-, over-, and correct estimates of peak values. The peak strains were overestimated. The peak strut forces were underestimated as a group. Modeling of the nonlinear behavior of gaps in the support did not improve the estimates for the force in the struts, The possible reasons for the differences and the effort on further analysis are discussed.