SHAM - high-level seismic tests of piping at the HDR

Using two servohydraulic actuators, each capable of generating 40 tons of force, high-level simulated seismic tests were performed on an in-plant piping system. The purpose of these experiments was to study the behavior of piping subjected to seismic excitation levels that exceed design levels manyfold and may result in failure/plastification of pipe supports and pipe elements, and to establish seismic margins for piping and pipe supports. The performance of six different dynamic pipe support systems was evaluated and the response, operability, and fragility of dynamic supports and of a typical U.S. gate valve were investigated. Data obtained in the tests are used to validate analysis methods. Preliminary evaluations of the test results lead to the observation that, in general, failures of dynamic supports (in particular snubbers) occur only at load levels that substantially exceed the design capacity. Pipe strains at load levels exceeding the design level threefold are quite small, an d even when exceeding the design level eightfold are quite tolerable. Hence, under seismic loading, even at extreme levels and in spite of multiple support failures, pipe failure is unlikely. Comparisons of linear pretest calculations with experimental data indicate that computed results may be nonconservative, underpredicting, in particular, peak dynamic-support forces