• Proceedings of the Korean Society of Disaster Information Conference
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• 2023.11a
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• pp.305-306
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• 2023

지반 침하 및 액상화 등에 따른 과도한 상대변위로 인한 매립배관 시스템의 손상을 저감시키기 위해 종종 벨로우즈 신축이음관은 사용된다. 벨로우즈 신축이음관의 성형과정에서 회선의 벽두께 감소와 같은 구조적인 불확실성이 발생할 수 있으며 특히, 벽두께 감소는 벨로우즈 신축이음관의 성능에 영향을 미칠 수 있다. 매립배관 시스템의 효율적인 유지관리를 위해 회선의 벽두께 감소에 의한 벨로우즈 신축이음관의 성능평가는 필요하다. 하지만 회선의 벽두께 감소가 벨로우즈 신축이음관의 성능에 미치는 영향을 조사하는 연구는 미미하다. 따라서 본 연구는 기초적인 연구로써 고충실도 유한요소 모델을 이용하여 단조하중을 받는 벨로우즈 신축이음관의 벽두께 감소에 의한 성능을 평가하고 민감도 분석을 수행하였다. 각 회선의 벽두께 감소를 20%로 적용하였을 때 최대하중은 약 3% 감소하는 것으로 나타났으며 2번 회선의 벽두께 감소가 최대하중 감소에 비교적 큰 영향을 미치는 것으로 나타났다.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2022.10a
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• pp.311-312
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• 2022

최근 발생한 경주 및 포항 지진으로 인해 다수의 매립배관 손상이 보고되었다. 벨로우즈 신축관이음은 기하학적 특성으로 인해 진동 및 침하 등으로 인한 손상을 저감시킬 수 있다. 벨로우즈 신축관이음관의 내진 성능평가에 대한 실험적 혹은 해석적 연구는 미미한 상황이다. 본 연구는 벨로우즈 신축이음관의 내진성능을 분석하기 위해 반복하중 기반의 실험적 연구를 수행하였다. 또한 실험결과를 기반으로 3차원 유한요소 모델을 구축하였으며 실험과 해석에서 얻어진 하중-변위 관계를 비교하였다. 해석 모델에서 전체적인 강성이 큰 것으로 나타났으며 최대 변위가 작용할 때 에너지 소산량은 약 10% 가량 큰 것으로 나타났다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.1
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• pp.46-52
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• 2024

The structural safety of expansion joints for piping systems has been drawing attention owing to ruptures and leaks of water pipes caused by earthquakes and road subsidence at soft ground. In general, metal bellows are installed as expansion joints to prevent various damages in the piping system. In this study, the seismic performance of a valve chamber system was evaluated by performing earthquake shaking table tests. To validate the benefits to structural safety of metal bellows in connecting steel pipes to valve chambers, the seismic tests were conducted on expansion joints (bellows) and general pipping, and the results were compared for durability. Strain gauges were attached to measure the effects of the input motion. As a result of the shaking table test, it was confirmed that the strain of the valve chamber structure and inflow or outflow steel pipes were decreased in 1/100, 1/20 by applied to the expansion joints.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.138-142
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• 2018

This study used HILS to test an expansion joint, which is vulnerable to the water hammer effect. The operation data for the HIL simulator was the length rate of the expansion joint by the water hammer, which was used for life prediction based on the vibration durability. For the vibration durability test, the internal pressure of the expansion joint was assumed to be a factor of the durability life, and the lifetime prediction model equation was obtained by curve fitting the lifetime data at each pressure. During the test, the major failure modes of crack and water leakage occurred on the surface of the bellows part. The lifetime prediction model typically follows an inverse power law model. The pressure is a stress factor, and the model is effective in only a specific environment. Therefore, another stress factor such as temperature will be added and considered for a mixed lifetime prediction model in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.424-429
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• 2018

In this study, an expansion joint that is susceptible to waterhammer was tested for its vibration durability. The operation data for the hydraulic actuator was the expansion length of the expansion joint when the waterhammer occurred. In the case of the vibration durability test, the internal temperature status of the expansion joint was assumed to be a stress factor and a lifespan prediction model was assumed to follow the Arrhenius model. A test was carried out by increasing the internal temperature status at $30^{\circ}C$, $50^{\circ}C$, and $65^{\circ}C$. By a linear transformation of the lifespan data for each temperature, a constant value and activation energy coefficient was induced for the Arrhenius equation and verified by comparing the value of a lifetime prediction model with the experimental value at $85^{\circ}C$. The failure modes of the ongoing or finished test were leakage, bellows separation, and internal deformation. In the future, a composite lifespan prediction model, including two more stress factors, will be developed.