地震を受ける配管系の疲労損傷確率評価法

抄録

When designing and evaluating the strength of the piping system of a nuclear power plant, ductile rupture or plastic collapse is often assumed to be the limit state. However, previous studies have reported that the primary failure mode of piping systems is fatigue. Therefore, it is important to conduct a fragility assessment of the piping system under the assumption that the failure mode is fatigue. In this study, the evaluation method of the relationship between the input acceleration and the fatigue failure probability in seismic response analysis was proposed by using probabilistic ε-N curve (P-ε-N curve). The linear cumulative damage was calculated as the ratio of equivalent cycle of earthquake to fatigue life of best-fit ε-N curve corresponding to the strain amplitude of P-ε-N curve of certain probability. The fatigue failure probability of this linear cumulative damage corresponds to the probability of the P-ε-N curve. Then, the fatigue failure probability of simple piping system was evaluated by the proposed method. The fatigue failure of the piping system was occurred on the elbow part. the circumferential strain was obtained by transforming from open-closed angle of elbow pipe.