401 動的荷重を受ける配管に対する確率論的信頼性手法の適用(OS4-1 LRFD法の展開)

概要

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It is a common recognition that piping of nuclear power plant has too much safety margin for seismic load. The reason why piping has too much safety margin is existing safety factors, for example. They are given by a deterministic or experimental way, so the structural safety margin is unclear. As a result, structures tend to have a too much safety margin. In this paper, we evaluated a safety margin for yielding of piping which was affected by a seismic load quantitatively by using a probabilistic reliability method. In application of a probabilistic reliability method, we applied limit state function method and first order reliability method (FORM) to the FEM piping model. Also, we evaluated a safety margin for fatigue by fatigue analysis which used hysteresis loop counting method and Miner's law. As a result, we revealed that although piping which is affected by seismic load has a small safety margin for yielding, it has a large safety margin for fatigue. So piping has a large safety margin on the perspective of piping soundness.
2010-10-09