금속 벨로우즈 신축관이음의 저온조건 내진성능에 대한 실험적 연구 = Experimental Study on the Seismic Performance of Metal-Bellows-Type Expansion Joints under Low-Temperature Condition

다국어 초록 (Multilingual Abstract)

Piping is a representative nonstructural element. Damage to pipes due to earthquake can be caused by inertia force, cyclic loads due to the phase difference between two support points, and relative displacement that exceeds the allowable deformation limit. In particular, many experimental studies have estimated that the failure mode of piping due to earthquakes is a low-cycle fatigue caused by large cyclic loads. Therefore, to prevent piping damage due to excessive seismic displacement, the application of a seismic separation joint or seismic separation assembly at a location where large relative seismic displacement can occur is required. Bellows, which are among the expansion pipe joints, can be applied as a seismic separation joint. In this work, an experimental study was conducted to analyze the change in seismic performance due to the temperature difference of a three-ply metal-bellows expansion joint. A gradual amplification cyclic-loading test was performed under room-temperature condition, and the same test was performed under a low-temperature condition of −20°C. The test results were compared, which confirmed that the displacement performance of the three-ply metal-bellows-type expansion joints could be reduced by approximately 10% under a low-temperature condition of −20°C.

국문 초록 (Abstract)

대표적인 비구조요소인 배관의 지진에 의한 손상은 관성력과 두 지지점 사이의 위상차에 의해 작용하는 반복하중 그리고 허용변형량을 초과하는 상대변위 등에 의해 발생할 수 있다. 특히 주요 손상모드는 큰 반복하중에 의한 저주기피로임이많은 실험적 연구를 통하여 알려졌다. 따라서 과도한 지진변위에 의한 배관의 손상을 방지하기 위하여 지진상대변위가 발생할수 있는 위치에 지진분리이음 또는 지진분리장치의 적용이 요구된다. 신축관이음 중 하나인 벨로우즈는 지진분리이음으로 적용할 수 있다. 본 논문에서는 3ply 금속 벨로우즈 신축관이음의 온도차에 의한 내진성능의 변화를 분석하기 위한 실험적 연구를수행하였다. 상온환경에서 점진증폭 반복하중재하실험을 수행하였으며, -20°C의 저온조건에서 동일한 실험을 수행하고 그 결과를 비교하였다. 실험 결과로부터, -20°C의 저온환경에서 금속벨로우즈의 변위성능은 약 10% 저하될 수 있음을 확인하였다.

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