• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.303-306
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• 2005

The cracking behavior of prestressed concrete members is important for the rational design of prestressed concrete structures. However, the test data on the cracking behavior of prestressed concrete structures are very limited. The purpose of the present study is to investigate the crack spacing and crack width in transversely post-tensioned decks of concrete box girder bridges under applied loading. For this purpose, large scale test members of concrete box girder segments were fabricated and tested. The crack widths, crack spacings and crack patterns were investigated for various load levels. The crack widths and steel strains were continuously monitored during the loading process. To derive a rational predicton equation for crack width, the bond characteristics of post-tensioned steel and nonprestressed rebar in the PSC members were explored first. This was done by measuring the strains of prestressing steel and nonprestressed rebar in the test members under loading. A simple equation for the prediction of maximum crack width in transversely post-tensioned concrete one-way slabs is proposed by considering bond characteristic of prestressing steel and nonprestressed reinforcement. The comparison of proposed equation with experimental data shows good correlation. The present study indicates that ACI and CEB-FIP code equations exhibit rather large deviation from test data on prestressed concrete members.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.681-684
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• 1999

The development of external prestressing methods has been one of the major trends in the concrete bridge constructions over the past decades. One of the promising methods to enhance the flexural strength of a externally prestressed girder is to place the tendons with large eccentricities. The test results in this study showed that the external prestressing of a composite girder increased the range of the elastic behavior, reduced deflections, increased ultimate strength, and added to the redundancy by providing the multiple stress paths. This study was conducted on the concrete bridges reinforced by the continuous girders and the external prestressing.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 춘계학술대회 논문집
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• pp.434-441
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• 1999

The newly proposed Precast Segmental Mettled (PSM), which makes use of precast elements for election, is relatively new, efficient and fast mettled for the construction of prestressed box girder bridges. A precast segment of 25m long pretensioned in the fabrication yard is transported by a special trailer and a launching truss to its final position. The segments are then connected in the site by post-tensioning to make a continuous prestressed concrete box girder bridges. The purpose of this parer is to analyze and evaluate the design of precast prestressed concrete box girder bridges. The detailed analyses including time-dependent behavior of PSM bridges are conducted. The major results and findings, which have been obtained from finite element analysis of PSM bridge, are discussed in this paper and these results will be a good base for the design and analysis of a new precast bridges.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.455-458
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• 2005

The Steel-Confined Prestressed Concrete Girder(SCP Girder) has been developed, which maximizes structural advantages of components (concrete, steel plate and tendon) and can be used to construct the middle or long span bridge with low-height girder. And recently, a continuous beam type of SCP Girder has been being developed to decrease size and self weight of girder in comparison with a simply-supported type. In this study, as part of developing the continuous beam type of SCP Girder, a new type of anchorage zone is proposed in order to address tendons effectively and decrease section size of SCP Girder efficiently. And also, the experimental test was carried out using a real scale specimen to examine the behavior of proposed anchorage zone.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.240-245
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• 2005

There has been a strong demand on more economic and lower depth girder bridges for short and medium span range, PRECOM, which is a new type steel-concrete composite girder, has been developed to realize a more economic bridge system with a lower depth girder. In the PRECOM girder bridge, a steel plate girder is simply supported and then concrete form is hung to girder. Thus, the self-weight of the concrete is loaded to the steel girder. To increase the resistance of concrete in the lower casing against tensile stress, compressive force is introduced by prestressed tendon To evaluate the manufacturability and performances of the completed bridge, four 15-m girders and a bridge specimen with two 20m girders wvere constructed. The camber during the construction and introduction of an appropriate compressive force was evaluated. Dynamic data were obtained through the modal testing of the completed girders. Static loading test was also conducted to examine cracks and evaluate the decrease in stiffness and failure behavior under extreme conditions.

• 대한토목학회논문집
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• 제30권3A호
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• pp.287-295
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• 2010

본 연구는 휨연결재와 횡방향 프리스트레스력으로 보강된 분절 PSC(Prestressed Concrete) 거더의 정적거동 성능을 검증하는데 목적이 있다. 정적거동 성능을 검증하기 위하여 4개의 분절거더와 1개의 일체거더를 제작하여 실험하였다. 분절거더와 일체거더는 동일 제원 및 재료를 적용하여 4.8 m 길이로 제작하여 실험하였다. 3개의 횡방향으로 보강된 분절거더의 정적거동 성능을 검증하기 위해 일체거더와 횡방향으로 보강되지 않은 분절거더가 기준이 되는 실험체로 실험을 수행하였다. 거더 중앙 경간에서 처짐을 측정하였으며 중앙 경간과 연결부에서 변형률을 측정하였다. 극한하중상태에서 횡방향으로 보강된 분절거더는 일체거더와 비교하여 극한강도가 동등이상의 성능을 나타내며 강성측면에서는 다소 불리하게 거동함을 알 수 있었다. 하지만, 횡방향으로 보강된 분절거더는 보강되지 않은 분절거더에 비하여 강도 및 강성측면에서 모두 우수한 성능을 나타내었다.

• Advances in concrete construction
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• 제10권1호
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• pp.71-79
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• 2020

Ultra-high-performance concrete (UHPC) is recognized as a promising material in future civil engineering projects due to its outstanding mechanical and durability properties. However, the lack of local UHPC materials and official standards, especially for prestressed UHPC structures, has limited the application of UHPC. In this research, a large-scale prestressed bridge girder composed of nonproprietary UHPC is produced and investigated. This work has two objectives to develop the mixing procedure required to create UHPC in large batches and to study the flexural behavior of the prestressed girder. The results demonstrate that a sizeable batch of UHPC can be produced by using a conventional concrete mixing system at any precast factory. In addition, incorporating local aggregates and using conventional mixing systems enables regional widespread use. The flexural behavior of a girder made by this UHPC is investigated including flexural strength, cracking pattern and development, load-deflection curve, and strain and neutral axis behaviors through a comprehensive bending test. The experimental data is similar to the theoretical results from analytical methods based on several standards and recommendations of UHPC design.

• Computers and Concrete
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• 제20권3호
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• pp.319-327
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• 2017

Studying the structural behavior of prestressed segmented girders is quite important due to the large use this type of solution in viaducts and bridges. Thus, this work presents a nonlinear three-dimensional structural analysis of an externally prestressed segmented concrete girder through the Finite Element Method (FEM), using a customized ANSYS platform, version 14.5. Aiming the minimization of the computational effort by using the lowest number of finite elements, a new viscoelastoplastic material model has been implemented for the structural concrete with the UPF customization tool of ANSYS, adding new subroutines, written in FORTRAN programming language, to the main program. This model takes into consideration the cracking of concrete in its formulation, being based on fib Model Code 2010, which uses Ottosen rupture surface as the rupture criterion. By implementing this new material model, it was possible to use the three-dimensional 20-node quadratic element SOLID186 to model the concrete. Upon validation of the model, an externally prestressed segmented box concrete girder that was originally lab tested by Aparicio et al. (2002) has been computationally simulated. In the discretization of the structure, in addition to element SOLID186 for the concrete, unidimensional element LINK180 has been used to model the prestressing tendons, as well as contact elements CONTA174 and TARGE170 to simulate the dry joints along the segmented girder. Stresses in the concrete and in the prestressing tendons are assessed, as well as joint openings and load versus deflection diagrams. A comparison between numerical and experimental data is also presented, showing a good agreement.

• 한국구조물진단유지관리공학회 논문집
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• 제15권5호
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• pp.75-81
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• 2011

최근 건설되는 교량은 철근 콘크리트 대신에 주로 프리스트레스트 콘크리트 교량이 주종을 이루고 있다. 프리스트레스 콘크리트 (PSC)는 철근 콘크리트 (RC)가 지니는 균열발생 문제, 철근의 부식, 누수 등 내구성에 미치는 약점을 보완할 수 있다. 또한 프리스트레싱으로 인한 인장영역의 보완으로 인하여 구조물의 크기를 줄일 수 있다. 하지만 이러한 구조용 주재료인 고강도 콘크리트의 경우는 밀도가 강도에 비하여 상대적으로 크기 때문에 상대적으로 자중을 증대시키는 문제가 있다. 따라서 자중을 감소시킬 수 있는 경량골재를 활용한 중공형 PPC 거더 (Hollowed Prefabricated Prestressed Concrete girder systems using Light Aggregate, 이하 HPPCLA)는 이러한 문제점을 해결할 수 있는 대안이 될 수 있다. 본 연구에서는 HPPCLA 거더의 성능시험 뿐 만 아니라 수치해석을 수행하였으며, 그 결과 HPPCLA 거더는 전형적인 휨파괴 형상을 나타내었다. 수치해석에서 예상한 바와 같이 PPC 거더의 사용하중인 110 kN에서는 완전한 탄성거동으로 구조물의 사용성에는 무리가 없을 것으로 판단된다.

• 한국철도학회논문집
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• 제8권3호
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• pp.267-275
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• 2005

Prestressed concrete girder(PSC girder) bridges have been used widely at the railway as well as highway because they are great in the functional and economical efficiency. Also they have the advantage of convenience of design and construction. However it could be easily verified that the section of PSC girder is excessive design, which has much redundancy against design loads. Thus, in this paper the formulation of the optimum design for PSC girder railway bridge is suggested and dominant design variables and constraints are inquired as performing the optimum design. In order to effective optimum design, design variables are formulated as PSC girder sectional dimension and girder space. The objective is adopted as total cost of PSC girder railway bridge. Also, constraints are formulated according to Korean railway design specification and considering construction-ability such as PS anchorage and girder space. Using the proposed optimum design system, optimum PSC girder railway bridge design has been performed. And from the results of analysis it is suggested to denote the optimum section which satisfies the structural safety and economical efficiency all together.