• 한국방재학회 논문집
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• 제10권5호
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• pp.27-33
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• 2010

본 연구에서는 2,000 kN 용량의 actuator를 이용, 12 m 경간의 실물 크기로 제작된 프리스트레스트 콘크리트 보의 구조성능 평가를 위한 실험을 수행하였다. 보의 양 단에는 접합을 위한 강판을 매립하였으며 시험체는 별도로 제작된 철골 보에 고력볼트접합 방식으로 세팅되었다. 프리스트레스트 콘크리트와 슬래브 콘크리트의 설계기준강도는 각각 50 MPa와 24 MPa이며, 인장 철근으로 사용된 2-HD25 철근은 매립강판의 구성요소 중 하나인 수직강판에 용접하였다. 실험은 변위제어법에 의하여 수행되었으며 10 mm의 변위를 증가시키며 loading과 unloading을 반복적으로 가력하였다. 실험결과를 살펴보면, 탄성거동구간에서는 약 88.34%, 비탄성거동구간에서는 약 86.97% 그리고 소성거동구간에서는 약 66.83%의 프리스트레싱에 의한 변위복원능력을 나타냄을 알 수 있었다.

• Computers and Concrete
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• 제19권2호
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• pp.191-201
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• 2017

External pre-stressing is often used in strengthening or retrofitting of steel-concrete composite beams. In this way, a proper numerical model should be able to trace the completely nonlinear response of these structures at service and ultimate loads. A three dimensional finite element model based on shell elements for representing the concrete slab and the steel beam are used in this work. Partial interaction at the slab-beam interface can be taken into account by using special beam-column elements as shear connectors. External pre-stressed tendons are modeled by using one-dimensional catenary elements. Contact elements are included in the analysis to represent the slipping at the tendon-deviator locations. Validation of the numerical model is established by simulating seven pre-stressed steel-concrete composite beams with experimental results. The model predictions agree well with the experimental results in terms of collapse loads, path failures and cracking lengths at negative moment regions due to service loads. Finally, the accuracy of some simplified formulas found in the specialized literature to predict cracking lengths at interior supports at service loading and for the evaluation of ultimate bending moments is also examined in this work.

• Steel and Composite Structures
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• 제21권2호
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• pp.343-356
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• 2016

As the common cast-in-place construction works fails to meet the enormous construction demand under rapid economic growth, the development of prefabricated structure instead becomes increasingly promising in China. For the prefabricated structure, its load carrying connection joint play a key role in maintaining the structural integrity. Therefore, a novel end plate bolt connecting joint between fully prefabricated pre-stressed concrete beam and high-strength reinforcement-confined concrete column was proposed. Under action of low cycle repeated horizontal loadings, comparative tests are conducted on 6 prefabricated pre-stressed intermediate joint specimens and 1 cast-in-place joint specimen to obtain the specimen failure modes, hysteresis curves, skeleton curves, ductility factor, stiffness degradation and energy dissipation capacity and other seismic indicators, and the seismic characteristics of the new-type prefabricated beam-column connecting joint are determined. The test results show that all the specimens for end plate bolt connecting joint between fully prefabricated pre-stressed concrete beam and high-strength reinforcement-confined concrete column have realized the design objectives of strong column weak beam. The hysteretic curves for specimens are good, indicating desirable ductility and energy dissipation capacity and seismic performances, and the research results provide theoretical basis and technical support for the promotion and application of prefabricated assembly frames in the earthquake zone.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2010년도 춘계 학술대회 제22권1호
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• pp.169-170
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• 2010

이 연구에서는 IPSC(Incrementally PreStressed Concrete)거더교에서의 적정 가로보 개수에 따른 구조적 거동이 분석되었다. 이를 위해지간 50m IPSC 거더교에 대하여 가로보의 개수가 늘어남에 따른 거동을 ABAQUS를 통해 유한요소해석이 수행되었다. 유한요소해석 결과 설계기준에 만족하고 경제적인 설계 및 시공성 향상을 위한 최적 가로보수가 판단되었다.

• International Journal of Concrete Structures and Materials
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• 제6권2호
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• pp.79-85
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• 2012

This paper presents the differences in growth of time-dependent strain values in reinforced cement concrete (RCC) and pre-stressed concrete (PSC) flexural members through experiment. It was observed that at any particular age, the time-dependent strain values were less in RCC beams than in PSC beams of identical size and grade of concrete. Variables considered in the study were percentage area of reinforcement, span of members for RCC beams and eccentricity of applied pre-stress force for PSC beams. In RCC beams the time-dependent strain values increases with reduction in percentage area of reinforcement and in PSC beams eccentricity directly influences the growth of time-dependent strain. With increase in age, a non-uniform strain develops across the depth of beams which influence the growth of concave curvature in RCC beams and convex curvature in PSC beams. The experimentally obtained strain values were compared with predicted strain values of similar size and grade of plane concrete (PC) beam using ACI 318 Model Code and found more than RCC beams but less than PSC beams.

• Computers and Concrete
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• 제27권1호
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• pp.63-71
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• 2021

In this study, a new stopping criterion, called "backward controlled stopping criterion" (BCSC), was proposed to be used in Genetic Algorithms. In the study, the available stopping citeria; adaptive stopping citerion, evolution time, fitness threshold, fitness convergence, population convergence, gene convergence, and developed stopping criterion were applied to the following four comparison problems; high strength concrete mix design, pre-stressed precast concrete beam, travelling salesman and reinforced concrete deep beam problems. When completed the analysis, the developed stopping criterion was found to be more accomplished than available criteria, and was able to research a much larger area in the space design supplying higher fitness values.

• 콘크리트학회논문집
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• 제12권4호
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• pp.91-101
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• 2000

As the computer related technology evolves a study for a practical use of real structure as well as its hteory for optimum design has been greatly advanced. But the study on optimum design of pre-stressed concrete beam(PSC-beam) bridge for the construction of national roads and highways in Korea is not sufficient. Since a standard section for the PSC-beam is proposed, it is practically used in designing the PSC-beam. It is noticed that the section using the current standard PSC-beam design to be an over-designed with its surplus safety factor. Therefore, it is necessary to consider economical PSC-beam section which automatically satisfies all requirement of design specifications. Thus, in this study, the optimum design methods of PSC-beam are carried out using the gradient-based search method and global search method. As a result of the optimum design method, it was confirmed that the design of PSC-beam has a serious properties to non-linearity and discontinuity. And the section that in economical and efficinet design methods than the current standard design method is proposed.

• Structural Engineering and Mechanics
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• 제61권1호
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• pp.117-124
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• 2017

Load testing is one of the important tests to determine if the structural elements can be used at the intended locations for which they have been designed. It is nothing but gradually applying the loads and measuring the deflections and other parameters. It is usually carried out to determine the behaviour of the system under service/ultimate loads. It helps to identify the maximum load that the structural element can withstand without much deflection/deformation. It will also help find out which part of the element causes failure first. The load-deflection behaviour of the road bridge girder has been studied by carrying out the load test after simulating the field conditions to the extent possible. The actual vertical displacement of the beam at mid span due to the imposed load was compared with the theoretical deflection of the beam. Further, the recovery of deflection at mid span was also observed on removal of the test load. Finally, the beam was checked for any cracks to assert if the beam was capable of carrying the intended live loads and that it could be used with confidence.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.545-551
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• 2006

Along with the steady development of Korean Railway construction technology, Contemporary society needs more modernized structures which can meet not only structural value but also aesthetic and environmental value. To follow this demand of society, Pre-Stressed Concrete U-girder bridge(Somg-Lim Gyo, L=330m) is introduced in 'JINJOO-KWANGYANG RAILWAY CONSTRUCTION PROJECT'. On the environmental point of view, the huge noise due to the operation of train can be reduced remarkably by the side beam of U-girder which is high enough to substitute soundproofing wall. Moreover, by aesthetic variation of the shape of outer beams and coping of piers, the exterior view of the bridge can be improved and in accordance with surroundings. Pre-Stressed Concrete U-Girders which are built up above the outer sides of slab deck make easier to secure the clearance of a bridge and make it possible to lower the distance of centroid between superstructure and railroad tracks.

• International Journal of Concrete Structures and Materials
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• 제11권2호
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• pp.261-273
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• 2017

The control of the deformative behaviour of pre-stressed concrete roof elements for a satisfactory service performance is a main issue of their structural design. Slender light-weight wing-shaped roof elements, typical of the European heritage, are particularly sensitive to this problem. The paper presents the results of deformation measurements during storage and of both torsional-flexural and purely flexural load tests carried out on a full-scale 40.5 m long innovative wing-shaped roof element. An element-based simplified integral procedure that de-couples the evolution of the deflection profile with the progressive shortening of the beam is adopted to catch the experimental visco-elastic behaviour of the element and the predictions are compared with normative close-form solutions. A linear 3D fem model is developed to investigate the torsional-flexural behaviour of the member. A mechanical non-linear beam model is used to predict the purely flexural behaviour of the roof member in the pre- and post-cracking phases and to validate the loss prediction of the adopted procedure. Both experimental and numerical results highlight that the adopted analysis method is viable and sound for an accurate simulation of the service behaviour of precast roof elements.