<p>The importance of the severe accident mitigation under beyond design-basis events (BDBEs) was realized to achieve the nuclear safety through the Fukushima accident. Failure mode estimation of essential components in nuclear facilities is necessary to take appropriate measures against the severe accident conditions. The failure mode of piping systems exposed to excessive seismic loading was found to be ratchet deformation followed by fatigue failure through many experimental tests in the past, whereas the failure mechanism of Test #37 of Pipe-fitting dynamic reliability program (PFDRP) conducted by EPRI was unexpected and remains unclear, as it was suspected to be failed in a plastic collapse after large deformation due to ratcheting. In the past research, the constant stress on the structure such as a dead-weight was revealed to significantly affect the failure mode and failure level of structures under seismic excitation. In this study, the constant stress components which can increase due to the ratchet deformation during a seismic excitation is focused and is analytically examined to clarify the effects on the failure mode of structures by using a cantilever structure with various dead-weight conditions and a constant cycles of sinusoidal waves which essentially represents the seismic loading with specific frequency ratios to establish the failure estimation of a structure exposed to seismic loading.&nbsp;</p>

Dynamic Behavior of a Simplified Cantilever With Progressive Static Loading due to Ratchet Deformation

Paper Proceedings: https://asmedigitalcollection.asme.org/PVP/PVP2021/volume/85314

ASME 2021 Pressure Vessels & Piping Conference (PVP2021)

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