플레이트 거더의 후좌굴거동 연구

정찬묵 우송대학교 산업연구소 2000 산업연구 Vol.2 No.1

The buckling of a plate girder web due to bending does not exhaust the load-carrying capacity of the web panel. Following buckling, however, out-of-plane deflection of the web plate cause a redistribution of stresses across the web plate. In general, the moments carried by the web plate alone at different cross sections along the plate are not constant due to different redistributions of stresses at each cross section. The equilibrium of moment can only be achieved by considering both the flanges and the web at a cross section. This causes nonzero membrane shear stresses along the boundary between the flanges and the web. In this study, the governing large deflection equations by Von Karman for a thin plate are solved with consideration of the membrane shear stresses along this boundary. The results are utilized to evaluate the bending moment at girder cross section.

교량 신축이음장치의 효율적 유지관리방안 연구

정찬묵 우송대학교 부설 산업연구원 1999 산업연구 Vol.1 No.1

The maintenance cost for bridge expansion joints, the most frequently failed element, was about 6000,000$ in 1992 which is approximately 48% of total bridge maintenance cost of national highway. In this study, the research was performed for the systematic maintenance of expansion joints with a particular emphasis on the following items: (1) Investigation of current conditions of expansion joints in service with a statistical approach according to the highway branch and the type of superstructure (2) Suggestion of a practical method to evaluate the performance for each type of joint currently used. The suggested method for evaluating the performance of joint was checked for 293 expansions joints on Chungbu highway on whih several types of expansion joint have been installed. Based on the results, strip seal joints and Mono Cell joint showed the most excellent performances. Plank seal joints such as Transflex were found to be not good due to the snow plow damage or braking vehicles, especially in ramps. Transflex designed for movement over 100mm had a very high frequency of failure.

강박스 합성형교의 슬래브타설 방식에 따른 지점부 곡률의 영향

정찬묵 우송대학교 1998 우송대학교 논문집 Vol.3 No.-

The purpose of this study is to treat design and construction problems related to steel box composite bridges which have been used widely, and to give guidelines based on the rational research. Specifically, in this study, the effect of slab concrete pouring methods was examined. Numerical results shows that the possibility of plastic shrinkage cracks at piers, the major drawback of the continuous pouring method, can be greatly decreased because the flexural moment of inertia of closed-shaped steel boxes used in Korea is about twice greater than that of U shaped open steel boxes used in other countries. The continuous pouring method is found to be the better in view of easier construction and fewer construction joints. Finally, field investigations will be suggested to verify the theoretical results.

슬래브 콘크리트 타설로 인한 강박스교의 거동에 관한 실험적연구

정찬묵 우송대학교 부설 산업연구원 2002 산업연구 Vol.4 No.1

This paper deal with the prediction of behavior of composite girder bridges according to the placing sequences of concrete deck. The variation of strain changes along bridge caused by slab casting is measured and the possibility of plastic shrinkage cracks is examined. The experimental results compared well with the analytical results. Meanwhile, the longitudinal stress distribution at top flanges to check the influence of shear lag is measured and compared to the relevant criterions in the Specifications.

슬래브 콘크리트 타설에 따른 강합성형교의 응력발생에 관한 연구

정찬묵 우송대학교 1999 우송대학교 논문집 Vol.4 No.-

This paper deals with the prediction of behavior of composite girder bridges according to the placing sequences of concrete deck. Based on a degenerate kernel of compliance function of the from of Dirichlet series, the time-dependent behaviors of bridges considering creep and shrinkage effects are simulated. The variation of bending moments along the bridge lenght caused by the slab casting sequence is reviewed.

레일식 죠인트에 대한 역학적 거동 연구

정찬묵 우송대학교 부설 산업연구원 1999 산업연구 Vol.1 No.2

As the length of bridges are getting longer recently, use of modulr expansion joints incorporating huge bridge movements are increasing. In this study, the research was performed for the basic elements of a modular joints, their mechanical behavior, and the structural analysis for a failed modular joint during service life. Based on the theoretical and experimental research results, it is found to be extrely important that fatigue behavior must be considered and very careful installation must be needed for modular joints. An analytical result for a failed modular joints showed that a damage on rubber spring is a main cause for an early failure which results possibly from poor installation.

교량 상판의 설계법 개선 연구

정찬묵 우송대학교 2000 우송대학교 논문집 Vol.5 No.-

Present study was accomplished for developing of enhanced design concept of more durable bridge deck. For this, firstly, existing design methods on bridge deck are compared. And additionally, laboratory test, structural analysis and field test were carried out. Static load tests and fatigue load tests were analysed on the basis of previous test results performed at the Korea Highway Corporation. The results showed that failure mechanism of bridge deck is punching shear failure, and fatigue life is mainly under the influence of the amount of bottom layer reinforcement and slab thickness. So, to improve fatigue characteristics, the minimum slab thickness should be increased. In this study, by summarizing the results of previous studies, enhanced bridge deck design method is proposed, and applied to a real bridge. It is expected that the fatigue life of bridge based on to proposed design method is 4 times longer than that of existing deck, with construction cost of bridge deck lowered by 5.5%.

고속도로 강교량의 피로조사에 관한 연구

정찬묵 우송대학교 1996 우송대학교 논문집 Vol.1 No.-

Since a study on the fatigue failure of bridge was conducted in 1930's , a full-scale study on fatigue behavior has been conducted from 1960's in America and continuous study is still in progress over the world. However, in Korea, researches on bridge fatigue behavior have been not enough due to the lack of understanding of fatigue failure. Thus it was not until 1992 that the fatigue provisions was specified in KHDC In this study, field inspections were conducted for 14 existing steel highway bridges whose service life is more tna 15 years. Also, a non-destructive inspection method for the welded members, a guide for rehabilitation and inspection of fatigue crack were suggested to improve the fatigue life of existing bridges or to remedy the weak details for fatigue in designing new steel bridges.

구조물의 연결부에서 전달함수합성법을 이용한 동응력 해석

김찬묵,공태식 국민대학교 생산기술연구소 2002 공학기술논문집 Vol.25 No.-

Researches on the FRF-based substructuring method have been mainly focused on vibratory response analysis. Present study is concerned about the application of the method to the dynamic stress analysis of a air-conditioner compressor mounting bracket in a passenger car. This is performed by using reaction forces that can be obtained by the FRF-based substructuring method. The air-conditioner system, composed of a compressor and bracket, is analyzed by using the FRF-based substructuring method. The experimental and numerical FRFs are combined to calculate the system responses and reaction forces at the connection point. The dynamic reaction forces plugged into the bracket FE model to compute the stresses of the bracket. Dynamic strains by the present method are compared with those from strain-gage test for bracket system on shaker. The comparison shows possibility of practical usage of the method for the real problem.

균열을 고려한 벽체의 Bond-Slip 관계 해석

정찬묵 우송대학교 2004 우송대학교 논문집 Vol.9 No.-

Cracks in concrete structures have many causes, e.g., hydration heat, plastic shrinkage, settlement, drying shrinkage, creep, thermal effects, chemical reactions, weathering, corrosion of reinforcements, errors in design and detailing, applied loads and etc. Concrete has inherently cracks. This means that all concrete structures have inevitably cracks. It is need to, therefore, evaluate whether such cracks in concrete structures, especially the important concrete structures like power plants, are harmful for the structures or not. The purpose of this research is to study the causes of cracks in concrete, to develop the analysis methods of the concrete structures considering the relevant causes, to evaluate and to check whether the structures are needed to repair, and to discuss on the proper repair methods for crack. In order to demonstrate the validity of this program, the walls were tested. This program predicts experimental results well.