균열을 갖는 콘크리트보에 대한 손상도의 정량적 평가

용환선,차범열,임태정 대한토목학회 1993 대한토목학회 학술발표회 논문집 Vol.1993 No.1

FRP 바닥판의 극한강도에 관한 실험적 연구

龍煥鮮 水原大學校 2004 論文集 Vol.22 No.-

Due to the vehicle loading and environmental attacks, deterioration of the bridge decks is usually accelerated. Bridge deck often requires repairs and deteriorated one will eventually be rehabilitated or replaced. For these reasons, service life of the conventional bridge deck is many times shorter than those of other bridge components. The FRPs are relatively new materials in bridge construction. With high strength to weight ratios, excellent durability, and low life-cycle costs of FRPs, FRP bridge decks can offer low dead load, minimum maintenance, and long service life. Due to the lightweight of FRPs, if the exissting concrete deck can be replaced with FRP deck, the load carrying capacity of the superstructure can be increased without strengthening the girders. In this paper, we have conducted an experiment on the ultimate strength and analyzed the static behavior of FRP bridge deck.

플랜지-거시트판 용접상세에서 피로균열의 성장

용환선 수원대학교 산업기술연구소 1997 산업기술연구소논문집 Vol.12 No.-

In this weld details of flange-gusset plate groove weld of plate girder and truss and stiffened truss of suspension bridge, stresses of the edge of the weld beed become complex and increase by stress concentration. During fabrication process, possibility of including weld defects or flaws in the welded parts become large. If the condition of stress states and weld defects are superimposed on the steel bridge detail, fatigue cracks are become major factor on decreasing in fatigue life of the steel bridge and reliability of serviceability of the bridge. In this study, the effects of the sudden change of section at the flange-gusset plate welded parts and differences of thickness of flange and gusset plate of the weld details are investigated.

압축플랜지의 극한강도에 대한 횡리브 구조상세의 영향

용환선 수원대학교 산업기술연구소 2003 산업기술연구소논문집 Vol.18 No.-

This paper intends to propose resonable design through to improve the structural details in intersection parts between longitudinal and transverse rib on compression flange or steel box girder. Nonlinear-finite element analyses have been carried out in order to evaluate the structural behavior or intersection parts considered welding condition, and parametric study was performed using the ratio or width and thickness or stiffened plate and longitudinal ribs. Also, By considering initial deformation and residual stress or connection parts as a effective factor, ultimate strength or stiffened plate was compared with each analytical models using the stress distribution and deformation. from the results, it is known that difference or structural performance in rib intersection parts considering the existence or welding is not influenced strength or stiffened plate without regard to ratio or width and thickness or stiffen plate.

단순 강형교의 응력범위 발생빈도 모형

용환선 수원대학교 산업기술연구소 1992 산업기술연구소논문집 Vol.7 No.-

Characters of stress wave induced by simultaneous traveling over simple steel girder bride were estimated. In the case of, trucks were traveled over the bridge with specified space, frequency of occurance of stress range for short span girder bridge were larger than that of long span bridge. Also, span of brige became larger, the small wave of stress were vanished and one of stress range occurs with one pass of simultaneous trucks travel.

Flange-Web 疲勞균열의 成長 限界

龍煥鮮 水原大學校 1987 論文集 Vol.5 No.-

The service life of steel bridged are reduced by simultaneous fatigue damage accumulation and loss of load capacity due to crack growth. In this study, to determine critical growth of fatigue cracks, critical crack length were estimated from forieitive of fatigue life and loss of load capacity. The durability of steel bridge holding crack in joint parts of flange-wed are dominated by fatigue and loss of load capacity unless Catastropic fracture occurs.

지방도 교량의 유지관리 현황파악을 위한 통계적 분석

龍煥鮮 수원대학교 산업기술연구소 1998 산업기술연구소논문집 Vol.13 No.-

Recently, according to increase of risk of collapse that is due to the deterioration and the unreliable construction of existing bridges, we have been concerned with maintenance of bridges. For the retension of serviceability in bridges during the service life, the maintenance of bridges are very important rather than design or construction stages. Thus, the maintenance of bridges corresponding with total service life are have to estimate for reservation of safety and serviceability on existing bridges. Thus, the inspection, examination, and study nationwide bridges have been performed for the bridge management system in Korea. In this, study, in order to evaluate the damage conditions of bridges, inspection report about 50 bridges performed safety inspection test are applied. From the result of examination for damage conditions, main damages occurred in concrete members are to include the efflorescence caused by water leakage, and the shrinkages caused by poor construction.

교통류의 통계적 해석으로부터 추정한 교량의 응력이력

용환선,최강희,최성권,Yong, Hwan Sun,Choi, Kang Hee,Choi, Sung Kweon 대한토목학회 1989 대한토목학회논문집 Vol.9 No.1

The stress history of a bridge is different depending on the characteristic of traffic flow. Because the flow is varied with vehicle type, weight and headway time etc., statistical analysis in bridges is necessary to estimate the history by traffic flow. By applying the statistical analyses in fracture mechanics, the remaining service life of the structure can be estimated. In this paper, 1)the statistical analysis of vehicle type, weight and headway time etc. to analysis randomness of traffic flow, 2)measuring and analysis of stress history of a real bridge, 3)reappearance of stress history by Monte-Carlo Simulation using constitution ratio of vehicle type, weight and headway time as probabilitic variable, 4)comparision of the calculated and modelled stress history, 5)calculation of reduction factor, 6)comparision of frequency of stress range depending on span length etc. were performed. From the results, the basic modelled stress history which is necessary for the method of estimation of the remaining service life of the structure could be suggested. 교량에 발생하는 응력이력은 교통류(traffic flow)의 성질에 따라 변하며, 교통류는 차종규성율, 차량중량, 차두시간간격(headway time)등에 따라 다르기 때문에 교량과 같은 휨부재에서 교통류에 의한 응력이력을 추정하기 위해서는 통계적 해석이 필요하며, 이것을 파괴역학에 적용함으로서 구조물의 잔존수명을 추정할 수 있을 것이다. 본 연구에서는 1)교통류의 불규칙성을 해석하기 위하여 차종구성율, 차량중량, 차두시간간격등을 통계적으로 분석 2)실제 교량에서의 응력이력의 측정과 분석 3)차종구성율, 차량중량, 차두시간간격을 확률변수로한 Monte Carlo 시뮬레이션에 의한 응력이력의 재현 4)실측 응력이력과 시뮬레이션한 응력이력의 비교 5)대상교량의 감소계수(reduction factor)의 계산 6)지간길이 변화에 따른 응력범위발생빈도의 비교등을 행하였다. 그 결과 시뮬레이션에 의한 응력이력 추정방법과 구조물의 잔존피로수명 예측에 필요한 기본적인 모형화된 응력이력을 제시하였다.

횡지지 시스템에 따른 소수주형 플레이트거더교의 구조거동에 관한 연구

龍煥鮮 수원대학교 산업기술연구소 2000 산업기술연구소논문집 Vol.15 No.-

Recently, a study on two or three I-girder bridge was active progressed in Japan and Europe for simplification of global structure. In order to evaluate the structural behaviour of two I-girder bridge according to types of lateral brece systems, this paper performed 3-dimension finite element analysis and focused to 2 I-girder bridges under design loads. In order to compare the structural characteristics of global structure, the following 3 parametric study was conducted. 1) stress characteristics of concrete slab and lower fiber of girder by types of lateral. brace system, 2) stress characteristics of concrete slab and lower fiber of girder by thickness of concrete slab, 3) stress characteristics of concrete slab and lower fiber of girder by spacing of a main girder. From the conclusions, we can confirm that structural behavior varying the lateral brace systems is nearly same. Thus we have to select the cross beam systems as a lateral brace system for simplification of construction works.

철도궤조(鐵道軌條) 및 용접연결부(鎔接連結部)에 대한 피로설계강도(疲勞設計强度)의 평가(評價)

용환선,Yong, Hwan Sun 대한토목학회 1988 대한토목학회논문집 Vol.8 No.2

The strength and load of structure are varied with the Passage of time, and become a process of probability. It is possible to estimate the reliability from the relation between strength and load. Considering the safety, It is reasonable to estimate allowable stress from the safety factor based on the reliability. In this study, the method to estimate probability of fracture, which is index of reliability for rail subjeict to long term fatigue load were examined. In estimation of reliablity it is meaningless to evaluate numerical value especially this difficult case estimating parameter of random variable. To overcome this problem, conventional design method estimating relative reliability were proposed. In this study the Cornell method were examined. The uncertainity of random variale, ie coefficient of variation which is the index of variation of strength and load were considered. The effect of uncertainity related to probability of fracture, and safety factor based on reliability were examined. The results of this study are followed. The reliability of weld metal were influenced by variation of strength more then load, and base metal were influenced by load. It is confirmed that the allowable stress range calculating with factor of safety based an reliability is conservative. 구조(構造)의 강도(强度)와 하중(荷重)은 시간(時間)이 경과함에 따라 변하며 확률과정(確率過程)이 된다. 이들의 상호관련성(相互關聯性)으로부터 신뢰도(信賴度)의 추정(推定)이 가능하다. 따라서 안정성(安定性)을 확보(確保)하기 위한 안전(安全)의 여유를 고려하는 경우 허용응력(許用應力)은 신뢰성(信賴性)에 근거한 안전율(安全率)로부터 구하는 것이 합리적(合理的)이다. 본(本) 연구(硏究)에서는 장기적(長期的)으로 피로하중(疲勞荷重)을 받는 철도(鐵道)레일을 대상(對象)으로 해서 신뢰성(信賴性)의 지표(指標)인 파괴확률(破壞確率)을 구하는 방법(方法)을 적용(適用)해 보았다. 신뢰도(信賴度)의 추정(推定)에 있어서 모수(母數)의 추정(推定)이 어려운 경우 파괴확률(破壞確率)의 수치계산(數値計算)은 의미가 없다. 이와 같은 문제점을 극복하기 위하여 상대적(相對的)인 신뢰성(信賴性)을 구하는 관용설계법(慣用設計法)이 제안(提案)되었다. 본(本) 연구(硏究)에서는 Cornell의 관용설계법(慣用設計法)을 적용(適用)하였다. 불확정요소(不確定要素)로서는 강도(强度)와 하중(荷重)의 변동계수(變動係數)를 사용하였고 이들의 파괴확률(破壞確率)에 대한 영향과 신뢰성(信賴性)에 근접(根接)한 안전율(安全率)을 검토하였다. 본(本) 연구(硏究)의 결과는 다음과 같다. 신뢰성(信賴性)에 있어서 용접재(鎔接材)는 강도변동(强度變動)의 영향을 크게 받고 모재(母材)는 하중변동(荷重變動)의 영향을 크게 받았다. 신뢰도(信賴度)에 근접(根接)한 안전율(安全率)로 구한 허용응력범위(許用應力範圍)는 안전측(安全側)에 있음을 확인(確認)하였다.