• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표대회 논문집(III)
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• pp.694-700
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• 1998

PSC box bridge by MSS construction method may not be set at cross section at one step. Web and bottom flange(U member) would be set at first, top flange will be set later with a time lag. In this case, U member and top flange concrete have different strain history. As two different aged section behaves as the composite section, there would happen the redistribution of stress. This is come from time-dependent strain characteristics of concrete itself. In this study, two models are considered, one with considering the set time of cross section and the other without. By performing longitudinal analysis of two models on considering construction stage, the stress differences of two are compared. As the analysis results show a considerable differences in the stresses of cross section between two models, the set time of cross section is needed for rational design f PSC box girder bridge.

• 한국구조물진단유지관리공학회 논문집
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• 제7권4호
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• pp.109-120
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• 2003

근래에 와서 도로교량의 형식 선정에서 미관에 대한 고려가 더욱 더 강조되는 추세 있으며, 미적으로 뛰어난 곡선교의 가설이 자연적으로 선호된다. 전달행렬법은 이론의 체계가 알기 쉽고, 응용범위가 넓은 점에서 구조해석법으로 범용성이 있는 것으로 주목되어 왔다. 전달행렬법에 의한 변단면 곡선 상자형교의 정적해석을 유한요소법과 비교하여 잘 일치함으로써 프로그램의 타당성을 검증하였다. 곡률반경과 중심각에 따른 해석 및 변단면 곡선식에 따른 지간비를 구하여 최적지간비와 변단면 비를 순수비틂이론에 의한 해석치를 분석하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.995-1000
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• 2000

Segmentally erected prestressed concrete box girder bridges have been widely used in Korean high speed railway. Segmental erection has been accomplished along the longitudinal direction and across the depth of cross section. The cross section is similar to a composite cross section, composed of old and new segments. Because these segments have different time-dependent creep and shrinkage properties, a stress redistribution takes place during the construction period. It is the main objective in this research to investigate this behavior. An actual bridge was instrumented with 96 vibrating wire embedded type strain gauges, 6 electronic type steel strain gauges, and 75 thermocouples. Two span continuous high speed railway bridge was selected. Two points of importance, such as the midpoint of the first span and the point of interior support, along the span of the girder were chosen to monitor the time dependent behaviors for an extended period of time. The data collection was starting just after concrete girder were cast and is still going on. According to the measured results, the strain distributions across the depth of the section at midspan and interior support were not continuous and the important redistribution of stresses takes place. Thus, rational design of prestressed concrete composite box girder bridges need.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1998년도 추계학술대회 논문집
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• pp.54-60
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• 1998

PSC box bridges by MSS construction method in high-speed railway may not be cast in place at one step. Web and bottom flange(U member) in the cross section are cast in place at first, then top flange will be cast in place later with some time lag. In this section, stress distributions of U member and top flange are different with those in generally complete cast in place cross section. In the composite section composed of two different aged members, the redistribution of stresses takes place. This results from time-dependent strain characteristics of concrete and the effects of forces applied at the various stages. For comparison in the present paper, two models, one with the composite cross section and the other with generally complete cast in place cross section, are analyzed. The longitudinal stress differences of two models on considering construction stages are compared. As the analysis results show the considerable differences in the stresses of cross section between two models, the composition of cross section is considered for rational design of PSC box girder bridge.

• 한국구조물진단유지관리공학회 논문집
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• 제26권3호
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• pp.111-119
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• 2022

모듈형 CFT 부재를 이용한 연속 강박스 거더의 단면강성 증대 및 프리스트레싱 공법은 긴장재로 프리스트레싱된 CFT 모듈을 강박스 거더 하부플랜지와 일체화한 후 긴장재를 제거함으로써 발생하는 CFT 모듈의 복원력을 강박스 거더 하부플랜지의 프리스트레싱력으로 이용하고 일체화된 CFT 모듈이 강박스 거더의 단면 강성을 향상시킨다. 본 연구에서는 CFT 모듈을 이용하여 일체화된 강박스 거더에 대한 프리스트레싱 도입의 적용성을 검토하기 위하여 하부플랜지를 모사한 실험체를 대상으로 CFT 모듈을 이용하여 프리스트레싱 도입 실험을 실시하고 유한요소해석으로 도입 프리스트레스를 평가하였다. 또한 실제 강박스 거더에 대한 프리스트레스 도입과 CFT 모듈을 통한 단면강성 증대효과를 확인하기 위하여 연속지점부에 적용 가능한 강박스 단면에 대하여 CFT 모듈에 도입된 프리스트레싱력 및 CFT 모듈의 단면제원에 따른 유한요소해석을 실시하고 이를 비교하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표대회 논문집(III)
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• pp.718-723
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• 1998

The program which could determine cross-sectional dimension of the prestressed concrete box girder bridges at the stage of preliminary design was developed using the optimal technique in this study. It could minimize the cost required in the design of box girder bridges and the construction with the full staging method. Objective cost function consisted of six independent variables such as height of cross-section, jacking force and thickness of web and bottom flange. The SUMT(Sequntial Unconstrained minimization Technique) was used to solve the constrained nonlinear minimization optimal problem. Using the program developed in this study, optimum design was performed for existing bridges with one cell cross section of constant depth. The result verify the compatibility of the program.

• 한국재난정보학회 논문집
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• 제15권4호
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• pp.626-633
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• 2019

연구목적 : 동일한 단면 2차 모멘트를 갖는 곡선 거더의 형상 변화에 따른 곡선 교량의 확률론적 안전성 평가인 지진 취약도 평가를 수행하고자 한다. 연구방법 : I, T, Box Shape 단면을 갖는 곡선 교량을 유한 요소 모델로 구축하였으며 경주 및 포항지진을 포함하여 24개의 입력지진을 적용하여 지진 취약도 평가를 수행하였다. 연구결과 : 거더의 응력에 대한 지진 취약도의 경우 T-Shpae 거더에서 가장 큰 파괴확률이 나타났으며 수평변위에 대한 지진 취약도의 경우 3개의 곡선 교량에서 비슷하게 발생하는 것으로 나타났다. 결론 : 3개의 곡선 교량에 대한 지진 취약도 분석을 수행하였으며 비틀림 저항이 가장 큰 Box-Shape 거더의 파괴확률이 가장 낮은 것으로 나타났다. 추후 연구에서는 추가적인 매개변수를 고려하여 지진 취약도 평가를 수행하고자한다.

• Steel and Composite Structures
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• 제34권3호
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• pp.423-440
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• 2020

In the recent years, steel box girder bridges have been extensively used due to high bending stiffness, torsional rigidity, and rapid construction. Therefore, researches related to this girder bridge have been widely conducted. This paper investigates the effect of residual stresses and geometric imperfections on the load-carrying capacity of steel box girder bridges spanning 30 m and 50 m. A three - dimensional finite element model of the steel box girder with a closed section was developed and analyzed using ABAQUS software. Nonlinear inelastic analysis was used to capture the actual response of the girder bridge accurately. Based on the results of analyses, the superimposed mode of webs and flanges was recommended for considering the influence of initial geometric imperfections of the steel box model. In addition, 4% and 16% strength reduction rates on the load - carrying capacity of the perfect structural system were respectively recommended for the girders with compact and non-compact sections, whose designs satisfy the requirements specified in AASHTO LRFD standard. As a consequence, the research results would help designers eliminate the complexity in modeling residual stresses and geometric imperfections when designing the steel box girder bridge.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 가을 학술발표회 논문집
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• pp.159-166
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• 1998

To study temperature effect of P.C. box girder bridge, field measurement was performed for six months, along with thermal analysis for the newly constructed viaduct of Gangbyun Highway in Seoul. Thermocouples were installed inside and surface of the flange and web of the box and temperature of box section md ambient temperature was measured. Measured environmental data are incorporated in finite element thermal analysis and computed temperature of the section was compared with measured one. Temperature gradient from thermal analysis was compared with Korean Highway Specification(1996)and the New Zealand Ministry of Works and Development code(1976). Thermal stress distribution across the box section was also compared.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.591-596
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• 2001

In case of continuous steel box-girder bridges, the magnitude of the longitudinal tensile stress on concrete in internal support is larger than the tensile strength of concrete. In this paper, the parametric study was performed to present the effective magnitude of the longitudinal prestress for reducing the longitudinal tensile stress to decrease under the tensile strength of concrete. The parametric study is conducted with changing the steel box-girder section and the span length of bridge. Three dimensional finite element analyses are conducted with ABAQUS program. The behavior of the steel box-girder bridge with prestress is investigated through experimental works on a analogous steel box-girder bridge model, and their results are compared with those of analytical studies.