아치 엣지보로 보강된 U형 합성교량의 실물실험을 이용한 구조거동 분석

김영구,임성순 한국복합신소재구조학회 2020 복합신소재구조학회논문집 Vol.11 No.1

최근 건설기술발전은 시공순서 세분화와 단면강성증진과 같은 기술변화로 선형조건 및 시공여건에 따라 요구되고 있는 다양한 교량 상부거더 형식이 개발되고 있다. 즉, 교량하부 형하공간이 부족한 곳에 설치하여야 하는 저형고 또는 장경간 거더와 같이 각각의 교량 설치 위치 상황에 따라 다른 형식을 요구되고 있다. 이러한 요구로 기존의 하로판형교를 개선한 아치엣지보로 보강된 U형 강합성 교량을 연구대상 교량으로 선정하게 되었다. 따라서 본 연구는 아치 형태로 변화는 I형 강재의 상부 압축부에 고강도 콘크리트를 충전시켜 각각의 주거더를 구성시킨 하로교형식의 강합성 U형거더를 실물제작하여 구조거동을분석하였다. 실험하중은 2단계로 구분하여 적용하였다. 1단계는 설계하중 1,200kN의 2.5배인 1차 실험하중 3,000kN을 재하하여실험오차와 재료비선형성을 확인하였다. 2단계 실험하중 2,000kN에서는 선형분포를 나타냈고 하중제거상태에서 잔류변형이 발생하지 않았다. 분석결과, 아치단면으로 변하는 주거더와 주거더 상단의 충전콘크리트의 합성은 단부의 압축력 집중현상과 같은아칭효과를 나타냈다. Recent advances in construction technology have led to the development of various superstructured girders, which are selected according to the road alignment and construction conditions. For example, long-span or low-height girders are used when the clearance under the girder is insufficient; in this condition, U-shaped steel– concrete composite girder bridges reinforced with arch edge girders are superior to the conventional steel trough bridges. In this study, the structural behavior of a trough-bridge containing high-strength concrete on the upper compression part of its I-shaped steel plate was analyzed through a full-scale model test. In the test, the loads were applied in two stages: in the first stage, the experimental errors and material nonlinearity were determined by applying a load of 3,000kN, which is 2.5 times the design load (1,200kN); in the 2nd stage, the load–displacement and load–strain curves showed a linear distribution and no residual deformation occurred in the unloading state with a load of 2,000kN. The results confirmed that the stiffness improvement and the arching effect such as the compressive force concentration at the end.

인장시험과 유한요소해석으로 구한 파단 진변형률을 이용한 진응력-진변형률 선도 획득

이경윤(Kyoungyoon Lee),김태형(Taehyung Kim),이형일(Hyungyil Lee) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.10

본 연구에서는 인장시험 및 유한요소해석으로 재료의 파단 진변형률을 구하고, 궁극적으로 재료의 진응력-진변형률을 얻는 방법을 제안했다. 먼저 인장시험으로 얻은 응력-변형률 선도를 네킹점에서 선형외삽해, 초기 진응력-진변형률 곡선을 설정하고, 이를 유한요소해석에 채택했다. 유한요소해석 후 Bridgman 계수 및 평판 수정계수들을 사용해, 단축상태의 하중-진변형률 선도를 얻어 파단진변형률을 실험-해석적으로 구했다. 이 예측 파단진변형률의 실험치 대비 오차는 3% 미만이다. 이렇게 구한 파단 진변형률과 이에 상응하는 파단진응력을 구해 파단점을 결정한다. 이어 네킹점과 결정한 파단점을 연결하는 네킹 후 진응력-진변형률 선형선도를 확보하고, 이를 네킹 전의 실험선도와 결합해 최종적으로 재료의 진응력-진변형률 선도를 완성했다. 본 연구에서 제시한 실험-해석적 진응력-진변형률 곡선 획득 방법은 SS400 평판시편과 같이 파단면적 측정이 어려운 경우, 그 유용함이 배가된다. In this work, we predict a true fracture strain using load-displacement curves from tensile test and finite element analysis (FEA), and suggest a method for acquiring true stress-strain (SS) curves by predicted fracture strain. We first derived the true SS curve up to necking point from load-displacement curve. As the beginning, the posterior necking part of true SS curve is linearly extrapolated with the slope at necking point. The whole SS curve is then adopted for FE simulation of tensile test. The Bridgman factor or suitable plate correction factors are applied to pre and post FEA. In the load-true strain curve from FEA, the true fracture strain is determined as the matching point to test fracture load. The determined true strain is validated by comparing with test fracture strain. Finally, we complete the true SS curve by combining the prior necking part and linear part, the latter of which connects necking and predicted fracture points.

MLS 가스켙의 하중-변위 선도 측정법

한병기(Byoungkee Han),최선웅(Seonung Choi),조성산(Sungsan Cho),장훈(Hoon Chang) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11

Full-beads of multi-layer steel engine head gaskets that are used to seal the combustion gas between the head and the block are subject to cyclic bending stresses due to the variation of the head/block gap during engine operation. The L-D curve of the full-bead formed on SUS304 thin plate is important for the sealing capacity assessment. Therefore the experimental method for measuring the L-D curve must be established in gasket company. In this study the rig and the data acquisition system for measuring the L-D curve is suggested. And the experimental results are shown. This results are compared with numerical results obtained by using ABAQUS package.

MLS 가스켙의 하중-변위 선도 측정법

韓秉基,崔善雄,李位魯 弘益大學校 科學技術硏究所 2005 科學技術硏究論文集 Vol.16 No.-

Full-beads of multi-layer steel engine head gaskets that are used to seal the combustion gas between the head and the block are subject to cyclic bending stresses due to the variation of the head/block gap during engine operation. The L-D curve of the full-bead formed on SUS304 thin plate is important for the sealing capacity assessment. Therefore the experimental method for measuring the L-D curve must be established in gasket company. In this study the rig and the data acquisition system for measuring the L-D curve is suggested. And the experimental results are shown. This results are compared with numerical rsults obtained by using ABAQUS package.

굽힘피로 하중을 받는 배관의 피로균열 발생수명 예측

곽상록,이준성,김영진,박윤원,Gwak, Sang-Rok,Lee, Jun-Seong,Kim, Yeong-Jin,Park, Yun-Won 대한기계학회 2001 大韓機械學會論文集A Vol.25 No.10

In order to improve Leak-Be(ore-Break methodology, more precisely the crack growth evaluation, a round robin analysis was proposed by the CEA Saclay. The aim of this analysis was to evaluate the crack initiation life, penetration life and shape of through wall crack under cyclic bending loads. The proposed round robin analysis is composed of three main topic; fatigue crack initiation, crack propagation and crack penetration. This paper deals with the first topic, crack initiation in a notched pipe under four point bending. Both elastic-plastic finite element analysis and Neuber's rule were used to estimate the crack initiation life and the finite element models were verified by mesh-refinement, stress distribution and global deflection. In elastic-plastic finite element analysis, crack initiation life was determined by strain amplitude at the notch tip and strain-life curve of the material. In the analytical method, Neuber's rule with the consideration of load history and mean stress effect, was used for the life estimation. The effect of notch tip radius, strain range, cyclic hardening rule were examined in this study. When these results were compared with the experimental ones, the global deformation was a good agreement but the crack initiation cycle was higher than the experimental result.

SA508-3재의 제하컴플라이언스법과 하중비해석을 이용한 파괴저항곡선 평가

임만배(Man-Bae Lim),차귀준(Gee-Jun Cha),윤한기(Han-Ki Yoon),안원기(Won-Ki An) 한국해양공학회 1998 韓國海洋工學會誌 Vol.12 No.1

The fracture resistance curve is one of most important and design techniques employed in nuclear pressure vessel structures. This study is to evaluate the J-R curve characteristics for the SA508C-3 by the unloading compliance method and load ratio analysis. The effect of strain aging for the exponential correlation of the J-R curve in this metal are investigated at room temperature, 200℃ and 300℃. The load ratio analysis method can evaluate the J-R curve by using the simple tension load-displacement curve only without the repeat of the unloading and loading. Therefore, the analysis by the proposed load ratio method has a merit, in comparison with the unloading compliance method, which can measure the crack length without the precision measurement equipment.

5182 Al합금판의 전기저항 점용접부 피로거동에 관한 연구

신현일,박용석,강성수 대한용접접합학회 1998 대한용접·접합학회지 Vol.16 No.2

On this study, the variations of hardness and microstructure were observed at he spot-welded part of 5182 alminum alloy sheets with thickness of 1.2 mm. The hardness of spot-welded part of aluminum alloy indicated the lowest value at nugget center. Also, the position where fatigue crack exists was investigated by surveying microstructure of the spot-welded sections. Mean load-deformation diagrams were obtained from static tensile test. Fracture was occurred completely within 5 mm after transforming elastic into plastic area. Fatigue test was stopped when the specimens of fatigue test had the final displacement of 0.2mm and measured fatigue bending angle and crack length. This study utilized them, investigated the relations between fatigue bending angle and fatigue crack length and made a estimation of the fatigue fracture life of resistance spot welded part of 5182 aluminum alloy sheet. The relative equation o fatigue crack length and fatigue failure life can be represented by {TEX}$L_{C}${/TEX}=α{TEX}$N_{f}^ {β}${/TEX}.

전단력을 받는 후설치 확장앵커의 콘크리트 파괴강도에 관한 실험적 연구

서성연 ( Seo Seongyeon ) 한국복합신소재구조학회 2021 복합신소재구조학회논문집 Vol.12 No.3

최근 건축물의 보수보강 및 리모델링 시 구조부재를 부착하거나 고정하는 데 있어서 시공의 유연성 및 용이성으로 후설치 확장앵커의 사용량이 점점 증가하고 있는 실정이다. 본 연구에서는 현장에서 비교적 용이하게 시공할 수 있는 후설치 확장앵커를 대상으로 비균열 무근콘크리트에 매입한 확장앵커의 연단거리 및 앵커간격를 변수로 한 전단실험을 통하여 확장앵커의 전단내력과 하중-변위관계를 분석하였다. 실험결과 연단거리 및 앵커간격에 비례하여 일정비율로 전단내력이 상승하였으며, 파괴모드는 강재앵커 파괴 및 콘크리트 파괴로 각각 나타났다. 그리고 실험결과를 ACI318-19 및 CCD설계기준과 비교분석 하였으며, 향후 보다 합리적인 후설치 확장앵커의 최적설계를 위한 기초자료를 제시하고자 한다. Recently, when buildings are repaired, reinforced, and remodeled, post-installed expansion set anchors have increasingly been used to attach or fix structural members owing to their flexibility and availability. The objective of this study is to investigate the shear strength and load-displacement relationships of post-installed expansion set anchors to facilitate building repair or construction. The experimental variables were edge distances and intervals of the expansion set anchors that were post-installed in uncracked and unreinforced concrete. The test results revealed that the capacity ratio increased by certain percentages according to the increase in the edge distances and anchor intervals. In addition, the fracture modes turned into concrete breakout and shear fracture of the set anchors. The test results were compared with those of the ACI and CCD design codes based on the edge distances and anchor intervals. This study also aims to present basic technical data of the post-installed expansion set anchors in building construction and remodeling.

인장시험과 유한요소해석으로 구한 파단 진변형률을 이용한 진응력-진변형률 선도 획득

이경윤(Kyoungyoon Lee),김태형(Taehyung Kim),이형일(Hyungyil Lee) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5

In this work, we predict a true fracture strain using load-displacement curves from tensile test and finite element analysis (FEA), and suggest a method for acquiring true stress-strain (SS) curves by predicted fracture strain. We first derived the true SS curve up to necking point from load-displacement curve. As the beginning, the posterior necking part of true SS curve is linearly extrapolated with the slope at necking point. The whole SS curve is then adopted for FE simulation of tensile test. The Bridgman factor or suitable plate correction factors are applied to pre and post FEA. In the load-true strain curve from FEA, the true fracture strain is determined as the matching point to test fracture load. The determined true strain is validated by comparing with test fracture strain. Finally, we complete the true SS curve by combining the prior necking part and linear part, the latter of which connects necking and predicted fracture points.

댐핑재가 도포된 차체 박육부재의 압궤특성

송상기,박상규,송찬일 한국마린엔지니어링학회 2003 한국마린엔지니어링학회지 Vol.27 No.1

The purpose of this study is to analyze the collapse characteristics of widely used spot welded section members coated damping material Y1000 and to develop an analysis method for acquiring exact collapse loads and energy absorption ratio. Hat-shaped thin-walled members have the biggest energy absorbing capacity in a front-end collision. The sections were tested on quasi-static and impact loads. Specimens with two type thickness, width ratio and spot weld pitch on the flange have been tested in impact velocities(6.73n0sec and 7.54n1sec) which imitate a real-life car collision. As a result, it was developed the system for acquiring impact energy absorbing characteristics of structure united thin-walled member and damping materials.