Experimental data from 14 test programs on dynamic response of piping are reviewed and evaluated. All tests demonstrate the conservatism of the Section III Level D stress limits for seismic loads on piping. Material plasticity significantly attenuates dynamic response. A straight pipe span was subjected to a dynamic input at 16 times the Level D allowable without collapse. An elbow was subjected to a dynamic input at 14 times the Level D allowable without failure by collapse or fatigue. However, the EPRI component tests demonstrate that collapse is a potential failure mode for certain configurations. The EPRI component tests also demonstrate that a fatigue failure in a single extreme earthquake event is possible. The seismic capability of piping is highly dependent on configuration, geometry, and fabrication details. One critical parameter is pipe frequency. Almost all the test data is on piping with a frequency of 4 Hz or greater. The BNL tests demonstrate that, as the frequency is reduced, response increases for the same input. In one of the few low frequency (1.4 Hz) tests, an EPRI elbow component collapsed. In another low frequency (2 Hz) test, two plastic hinges developed in a pipe span, but strain hardening prevented collapse.
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| Number of Pages : | 176 |
| Published : | 1997 |
