After the Fukushima Dai-ichi Nuclear Power Plant (NPP) accident, the importance of consideration for beyond design basis accident (BDBA) is widely recognized. In considering BDBA, it is necessary to understand failure modes of structures beyond the conventional design assumption, and to manage the accident progress and consequence with the best estimation of structural ultimate behaviors. To investigate the failure behavior of piping systems under the beyond design basis seismic loads, the authors have proposed a new experimental procedure to use pipes made of the simulation material instead of steel pipes in the previous study. Lead-antimony (Pb-Sb) alloy was adopted as the simulation material, and shaking table test on the piping system model with single elbow made of Pb-Sb alloy were conducted in the previous study.

As the next step of the experimental study, shaking table tests on the more realistic piping system models were conducted. The piping system models had two elbows made of Pb-Sb alloy, one additional mass, and two fixed anchors. Input motions were sinusoidal wave. The failure modes of the piping system were examined by varying the additional mass and frequency of the input sinusoidal wave. From the experiments, it was shown that the possible failure mode was the ratchet and subsequent collapse, and it seemed that the occurrence of the failure mode depended on the ratio of the specimen's natural frequency to the input frequency, and the ratio of additional mass weight to the limit mass weight.

Inelastic Finite Element Method (FEM) analyses were also conducted on the two-elbow piping system models. It was shown that the failure behavior of the piping system model made of the simulation material was generally well reproduced by the FEM analysis.


Investigation on Failure Behavior of Two-Elbow Piping System Models Made of the Simulation Material Under Excessive Seismic Loads

Division / Sponsors: 
Pressure Vessels & Piping (PVP)


Paper Proceedings: https://asmedigitalcollection.asme.org/PVP/PVP2020/volume/83815

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