• 대한토목학회논문집
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• 제26권1A호
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• pp.67-74
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• 2006

장대교량 건설의 증가와 강교량의 합리화 추세에 따라 최근 후판 강재의 사용이 늘어가고 있다. 후판 부재의 현장이음에서는 M30 고장력볼트와 같은 대형볼트의 사용이 불가피하나 현재 국내 시방기준에는 대형볼트의 사용에 대한 규정이 없는 실정이다. 따라서 본 연구에서는 대형볼트인 M30 고장력볼트의 사용성을 검토할 목적으로 볼트의 크기와 부재의 판두께를 변수로 하여 릴렉세이션과 미끄러짐 거동을 시험적으로 분석하였다. 또한, 유한요소해석을 통하여 판두께의 차이에 따른 내부압축응력을 분석하였으며, 이를 볼트축과 볼트구멍 내벽에 부착한 변형률게이지로부터 얻어진 응력분포와 비교하였다. 그 결과 M30 고장력볼트를 사용한 경우에도 릴렉세이션은 10%를 초과하지 않았으며, 미끄러짐 계수도 시방기준을 초과하는 충분한 내력을 확보하는 것으로 나타나 사용상에 문제가 없는 것으로 판단된다.

• Journal of Advanced Marine Engineering and Technology
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• 제16권5호
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• pp.60-66
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• 1992

In most cases a structure consists of the assembly of some substructures, we assemble them with various joints, and the structure is fixed to a foundation through mounts. In case of the structure with rigid joints like welding, the Finite Element Mothod could be easily used to analyize the structure's characteristics, but in case of the structure with elastic joints like bolts or rivets, it might be difficult to analyize it by taking account of joint's rigidities, with the conventional method. This paper proposes the method to identify the joint rigidities by the Sensitive Analysis Method and the Optimization Techniques. And the proposed method applied to identify the rigidities of 4 bolts to combine 2 plates(500mm long, 100mm wide, 3.15mm thich). The analized results were well coincident with the experimental results. To confirm the reliability 0 the rigidities identified, another trial was done for the stucture to combine other 2 plates with same joints. The results were good too. This paper is proposin the identifying method of the joint rigidity of a structure, and it could be used for the data base of the joint rigidity and for the guidance to select joint stiffness.

• 대한기계학회논문집A
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• 제27권6호
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• pp.930-937
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• 2003

The extension of design life among power plants is increasingly becoming a world-wide trend. Kori #1 unit in Korea is operating two cycle. It has two man-ways for tube inspection in a steam generator which is one of the important components in a nuclear power plant. Especially, stud bolts fur man-way cover have damaged by disassembly and assembly several times and degradation for bolt materials for long term operation. It should be evaluated and compared by ASME Code criteria for integrity evaluation. Integrity evaluation criteria which has been made by the manufacturer is not applied on the stud bolts of nuclear pressure vessels directly because it is controlled by the yield stress of ASME Code. It can apply evaluation criteria through FEM analysis to damaged female threads and to evaluated safety fer helical-coil method which is used according to Code Case-N-496-1. From analysis results, we found .that it is the same results between stress intensity which got from FEM analysis on damaged female threads over 10％ by manufacture integrity criteria and 2／3 yield strength criteria on ASME Code. It was also confirmed that the helical-coil repair method would be safe.

• Steel and Composite Structures
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• 제11권4호
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• pp.291-305
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• 2011

The new structure consisting of continuous compound spiral hoop reinforced concrete (CCSHRC)column and steel concrete composite (SCC) beam has both the advantages of steel structures and concrete structures. Two types of beam-to-column connections applied in this structural system are presented in this paper. The connection details are as follows: the main bars in beam concrete pass through the core zone for both types of connections. For connecting bar connection, the steel I-beam webs are connected by bolts to a steel plate passing through the joint while the top and bottom flanges of the beams are connected by four straight and two X-shaped bars. For bolted end-plate connection, the steel I-beam webs are connected by stiffened extended end-plates and eight long shank bolts passing through the core zone. In order to study the seismic behaviour and failure mechanisms of the connections, quasi-static tests were conducted on both types of full-scale connection subassemblies and core zone specimens. The load-drift hysteresis loops show a plateau for the connecting bar connection while they are excellent plump for bolted end-plate connection. The shear capacity formulas of both types of connections are presented and the values calculated by the formula agree well with the test results.

• Smart Structures and Systems
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• 제18권6호
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• pp.1189-1202
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• 2016

This paper describes an application of wavelet analysis for damage detection of a steel frame structure with bolted connections. The wavelet coefficients of the acceleration response for the healthy and loosened connection structure were calculated at each measurement point. The difference of the wavelet coefficients of the response of the healthy and loosened connection structure is selected as an indicator of the damage. At each node of structure the norm of the difference of the wavelet coefficients matrix is then calculated. The point for which the norm has the higher value is a candidate for location of the damage. The above procedure was experimentally verified on a laboratory-scale 2-meter-long steel frame. The structure consists of 11 steel beams forming a four-bay frame, which is subjected to impact loads using a modal hammer. The accelerations are measured at 20 different locations on the frame, including joints and beam elements. Two states of the structure are considered: healthy and damaged one. The damage is introduced by means of loosening two out of three bolts at one of the frame connections. Calculating the norm of the difference of the wavelet coefficients matrix at each node the higher value was found to be at the same location where the bolts were loosened. The presented experiment showed the effectiveness of the wavelet approach to damage detection of frame structures assembled using bolted connections.

• 터널과지하공간
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• 제25권5호
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• pp.470-486
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• 2015

2-아치 터널은 터널의 간격이 매우 좁아서 병렬 터널에 비해 점유 면적이 작으나 경제적이지 못하다. 병렬 터널은 경제적이긴 하지만 2-아치 터널보다 점유 면적이 커서 용지의 매입이 어려운 경우에는 문제가 될 수 있다. 새로운 설계는 이 두 터널을 터널의 간격이 점차 증가하는 제3의 병렬터널로 연결시키는 것이다. 접속터널의 필라는 폭이 매우 좁을 수 있기 때문에 이 새로운 설계를 불량한 암반에 적용하려면 검증이 필요하다. 이에 4등급 및 5등급 암반에 대해 2차원 및 3차원 수치해석을 이용하여 2가지 방법으로 안정성 검토를 수행하였다. 검토 결과, 중앙 필라가 텐션 볼트로 적절히 보강된다면 터널 심도가 직경의 5배 이하인 경우에는 적용이 가능하였다.

• 한국해양공학회지
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• 제30권5호
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• pp.356-360
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• 2016

Recently, the lifetime extension of nuclear power plants has been considered. Thus, it is necessary to consider facility safety management and economic management. However, when the bolts in nuclear power plants are replaced and the turbines of nuclear power plant are disassembled, numerous problems are found in relation to stuck bolts in clamping parts. In order to solve these problems, a hybrid vacuum chamber was first designed and manufactured. It can perform arc ion plating and sputtering, which were used to deposit Ti/TiN on an A913 B7 bolt. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were conducted to determine the composition and characteristics of the bolt, and tests were conducted to determine how long the bolt could endure under various conditions in a nuclear power plant. The SEM and XRD results clearly showed a continual and even coating layer. When this TiN-coated bolt is used in a nuclear power plant, the lifetime can be extended compared to a conventional bolt, but it is necessary to determine what additional properties are required.

• 대한토목학회논문집
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• 제26권4A호
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• pp.597-604
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• 2006

FRP재료를 이용한 바닥판은 교량생애주기비용 측면에서 재료가 고강도이고 내구성이 우수하여 유지관리를 최소화하고 교체주기가 길게 되므로 경제성이 우수할 것으로 기대되며, 프리캐스트 부재로 가설되므로 시공성이 우수하다. 본 연구에서는 FRP바닥판 시공시 합리적이며 경제적인 강재거더와의 연결방법을 검토하기 위해 연결볼트를 이용한 7가지 기계적 연결지점 조건에 대한 하중재하실험 및 해석을 수행하였다. 실험결과 향후 FRP바닥판과 강재거더 사이의 전단력에 대해 볼트의 강도가 안전측에 있다면 시공시의 효율성 및 경제성을 고려하여 지그재그 체결을 하여도 구조계는 안전할 것으로 평가되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.497-499
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• 2004

Due to a typhoon named MAEMI on Sep12, 2004, 7 transmission towers collapsed and 3 were damaged in the Gyeongnam and Busan areas. These caused long-term black-outs in Goeje-do. When a transmission tower collapses or is damaged, Construction will take more than 2 months and this will be accompanied by long-term black-outs. Therefore a temporary iron pole is used in such emergencies. Current temporary rehabilitation angle steel iron Pole consistes of around 800 members, 2,800 bolts and it takes about 5 days to construct a temporary transmission line. Consiquently wide black-outs occur during the construction of the temporary transmission line. To reduce black-out time, the construction period must be reduced as much as possible. This paper presents new methods to reduce temporary transmission line construction time to within 48 hours by applying a self-reliance assembling method instead of the current man power assembling method and by modulizing each angle steel with duralumin.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 A
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• pp.494-496
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• 2004

Due to a typhoon named MAEMI on Sep12, 2004, 7 transmission towers collapsed and 3 were damaged in the Gyeongnam and Busan areas. These caused long-term black-outs in Goeje-do. When a transmission tower collapses or is damaged, Construction will take more than 2 months and this will be accompanied by long-term black-outs. Therefore a temporary iron pole is used in such emergencies. Current temporary rehabilitation angle steel iron Pole consistes of around 800 members, 2,800 bolts and it takes about 5 days to construct a temporary transmission line. Consiquently wide black-outs occur during the construction of the temporary transmission line. To reduce black-out time, the construction period must be reduced as much as possible. This paper presents new methods to reduce temporary transmission line construction time to within 48 hours by applying a self-reliance assembling method instead of the current man power assembling method and by modulizing each angle steel with duralumin.