• 한국구조물진단유지관리공학회 논문집
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• 제25권1호
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• pp.112-119
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• 2021

지진하중으로 인한 배관계통의 파괴모드는 라체트를 동반하는 저주기 피로파괴이며 비선형 거동이 집중되고 파손이 발생하는 요소는 엘보인 것으로 나타났다. 본 연구에서는 저주기 피로에 의한 SCH 40 3인치 탄소강관엘보의 파괴기준을 정량적으로 표현하기 위하여 한계상태를 누수로 정의하고 면내반복가력실험을 수행하였다. 배관계통에서 지진하중에 취약한 요소인 탄소강관엘보에 대하여 모멘트-변형각의 관계를 이용한 손상지수를 나타내었으며 힘-변위의 관계를 이용하여 산정된 손상지수와 비교-분석하였다. 탄소강관엘보에 대하여 반복되는 외력에 의한 소산에너지에 기반을 둔 손상지수로서 누수가 발생한 한계상태를 정량적으로 표현하였다.

• 한국지진공학회논문집
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• 제26권1호
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• pp.13-22
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• 2022

This study proposes a low-cycle fatigue life derived from measurement points on pipe elbows, which are components that are vulnerable to seismic load in the interface piping systems of nuclear power plants that use seismic isolation systems. In order to quantitatively define limit states regarding leakage, i.e., actual failure caused by low-cycle fatigue, in-plane cyclic loading tests were performed using a sine wave of constant amplitude. The test specimens consisted of SCH40 6-inch carbon steel pipe elbows and straight pipes, and an image processing method was used to measure the nonlinear behavior of the test specimens. The leakage lines caused by low-cycle fatigue and the low-cycle fatigue curves were compared and analyzed using the relationship between the relative deformation angles, which were measured based on each of the measurement points on the straight pipe, and the moment, which was measured at the center of the pipe elbow. Damage indices based on the combination of ductility and dissipation energy at each measurement point were used to quantitatively express the time at which leakage occurs due to through-wall cracking in the pipe elbow.