• 도로교통
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• s.92
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• pp.81-83
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• 2003

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.3
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• pp.251-259
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• 2004

The prediction accuracy of prestress plays an important role in the quality of maintenance and the decision on rehabilitation of infrastructure such as prestressed concrete bridges. In this paper, the Bayesian statistical method that uses in-situ measurement data for reducing the uncertainties or updating long-term prediction of prestress is presented. For Bayesian analysis, prior probability distribution is developed to represent the uncertainties of creep and shrinkage of concrete and likelihood function is derived and used with data acquired in site. Posterior probability distribution is then obtained by combining prior distribution and likelihood function. The numerical results of this study indicate that more accurate long-term prediction of prestress forces due to creep and shrink age is possible.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.1
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• pp.91-101
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• 2008

Structural analysis models to develop live load distribution factors of simply supported prestressed concrete I-girder bridge should have the precision of the analysis results as well as modeling simplicity. This is due to the numerous frequency of structural analysis needed while developing live load distribution factors. In this study, an appropriate structural analysis model is selected by comparing previous researchs studies and models used in practical design. Also, the influence by the flexural stiffness of barrier and diaphragm on the live load distribution had been analyzed through comparing the numerical analysis and experimental tests. As a result, the model that the eccentric girder and the barrier and diaphragm are connected to the deck plate was appropriate in satisfying both accuracy and simplicity for structural analysis of simply supported prestressed concrete I-girder bridge. However, the barrier was analyzed to have insignificant influence on the live load distribution in spite of its variation of stiffness. The eccentric diaphragm showed little influence at 25% or higher of flexural stiffness. From the results, a model that the girder is rigidly connected to the deck plate in consideration of the eccentricity, the barrier is ignored and the whole section of diaphragm is supposed to be valid without eccentricity is decided as the most appropriate structural model to develop the live load distribution factors of simply supported prestressed concrete I-girder bridge in this study.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3A
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• pp.287-295
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• 2010

The main purpose of this study is to investigate the static behavior of spliced prestressed concrete girder with bending moment connector and lateral prestressing. Four (4) spliced girders and one (1) monolithic girder had been fabricated and tested to compare their static behaviors. Same geometry and materials are used to fabricate these spliced and monolithic girders. A monolithic girder and one (1) spliced girder without lateral bending connector are used as control specimens to estimate the performance of three (3) spliced girders with lateral bending connector. Deflections at the middle of girders have been measured for evaluation. Also, strains of the concrete at the middle of span and connection points have been measured. It was found from the result that laterally strengthened spliced girders showed improved ultimate strength but less stiffness compared to the monolithic girder at the ultimate state. Laterally strengthened spliced girder also showed improved strength as well as improved stiffness compared to the spliced girder without lateral strengthening.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.2
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• pp.51-58
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• 2008

This study is to investigate the ultimate shear load of prestressed girder made of Ultra High Performance Fiber Reinforced Concrete (UHPFRC). Nine girders were tested until failure in shear. An analytical model to predict the ultimate shear load was formulated based on the Two Bounds Theory. A fiber reinforcing model was constituted based on the random assumption of steel fiber uniform distribution. The predicted values were compared with the conventional predictions and the test results. The proposed equations for computing the ultimate shear strength can be used for the ultimate failure status analysis, which could also be utilized for numerical limit analysis of prestressed UHPFRC girder. The established fiber reinforcing theoretical model can also be a reference for micro-mechanics analysis of UHPFRC.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.6A
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• pp.495-502
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• 2010

A study for the nonlinear analysis method of flexural behavior of concrete girders strengthened with unbonded prestressed CFRP plates is presented. The concrete girders strengthened with unbonded prestressed CFRP plates exhibit more complex nonlinear behavior due to the slip between the concrete girder and the CFRP plates than the case of bonded CFRP plates. The unbonded CFRP plate is modeled as an assemblage of the curved elements both ends of which are rigidly linked to the nodes of fibered frame elements. The slip effect of the unbonded CFRP plate is taken into account using the force equilibrium relationship at each node. To evaluate the validity and the capability of the proposed analysis method, the ultimate analysis results of the concrete beams strengthened with unbonded prestressed CFRP plate are compared with the experimental results obtained from other investigators. The proposed analysis method is found to predict ultimate behaviors of these beams fairly well. Additionally the time-dependent deformations of the concrete beam seems to have little influence on the ultimate behaviors of concrete beams strengthened with unbonded prestressed CFRP plate, and the cracks of the concrete beam which occurred before strengthening it with CFRP plate are found to have almost no influence on the ultimate capacity of the beam.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.04a
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• pp.36-41
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• 1994

프리캐스트 프리스트레스트 콘크리트 상자형 교량의 정착부에 프리스트레스 힘이 도입되면, 과다한 국부집중 하중으로 인하여 균열이 발행할 수 있으며, 최근 이러한 교량의 건설시 텐던을 따라가며 심각한 균열이 발생한 경우가 있다. 본 논문은 프리캐스트 프리스트레스트 콘크리트 상자형 교량의 정착부에 발생하는 국부집중 응력의 분포 특성을 규명하고, 이를 토대로 파괴기구 고찰함에 목적이 있다. 이를 위하여 정착부 파괴에 직접적인 영향을 미치는 단면의 형상, 텐던의 배치상태, 국부보강 철근의 형태 및 구조보강 철근량 등을 변수로 하는 역학적 거동 실험 및 해석 연구가 수행되었다. 위의 실험 및 해석연구결과 정착부 파괴양상이 규명되었으며, 프리스트레스 정착부의 새로운 파괴기구 개념이 제시되어, 정착부 파괴과정을 적절히 설명하고 있다.

• Journal of Korean Society of Steel Construction
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• v.17 no.5 s.78
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• pp.637-648
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• 2005

Innovative prestressed steel plate girders were presented in this study. Hot-rolled H beams were loaded first, then relatively high-strengthsteel plates were welded on the top and bottom flanges of preloaded H beams. Finally, high prestressed plate (HiPP) girder was manufactured by simply releasing prestresses of rolled beams. To verify prestress distributions induced in this girder, the experimental study was conducted and some guidelines to manufacture these girders effectively were addressed. In addition, methods to determine the allowable bending stress of HiPP girders and to check welding stresses were addressed for design of temporary bridges. The efficiency and effectiveness of the present girder were demonstrated through design examples of temporary bridges adapting the prestress-induced girder or the plate girder of the same section without prestresses. As a result, it has been found to be possible that the span length of HiPP girders for temporary bridges is longer than that of girders without prestresses.

• Journal of the Society of Disaster Information
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• v.12 no.4
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• pp.422-431
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• 2016

This study was evaluated in the performance of the connection according to the details of the concrete casing segment in the prestressed composite girder by fabricating and testing specimens with different segments. A total of four comparative specimens were fabricated by using the variables of general composite girders, reinforcement or non-reinforcement, and details of reinforcing bars in the segments so as to evaluate the structural behavior of steel girders. In addition, the possibility of non-cracking grade design of segmented composite girders as well as the effects of stiffness and strength according to the loop connection types after cracking were analyzed, and the appropriateness of the crack width control both the embedded steel plate and the concrete surface were evaluated.

• Magazine of the Korea Concrete Institute
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• v.28 no.3
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• pp.40-45
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• 2016