• Proceedings of the KSR Conference
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• 2006.11b
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• pp.365-375
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• 2006

The HR Plates made hot rolled coils is lower than general structural steel plates in price. No difference between general steel plates and HR Plates with thickness up to 22mm are found in most characters such as cutting operation, fabrication and even welding. It can be concluded that HR Plates with thickness up to 22mm can be applied to flanges and webs of any girders as well as longitudinal ribs, longitudinal and vertical stiffeners of steel bridges appropriately. To increase the demand of HR Plates with thickness up to 22mm, it is necessary that HR Plates is applicable to full member in steel bridge including main girder.In this study, availabilities of the narrow steel box girder of light railway transit with HR Plate width as a main member are discussed. For application of HR Plate to steel bridge with 50m span or more, new support systems in three types are presented. Computational analysis is performed in 15 bridge models of light railway transit with beam element and plate element. As a analysis results, three models in light railway transit are presented. We finally come to the conclusion that HR Plates can be apply to narrow steel box girder in the light railway transit.

• Journal of Korean Society of Steel Construction
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• v.15 no.3
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• pp.231-239
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• 2003

Many box girder bridges have been constructed during the past several decades due to their large bending and torsional rigidities as well as aesthetic considerations. However, box girders have shortcoming in that the cross section distorts under an eccentric loading and warps out of the section plane. Therefore, in order to reduce distortional stresses such as distortional warping and transverse bending normal stresses, diaphragms were generally installed in the box girders. Shapes of the diaphragms in steel-box-girder bridges constructed up to date were solid-plate, frame, and truss types. The objectives of this study using parametric study were to evaluate the appropriate stiffness ratio of intermediate diaphragms and then to propose the effective spacing and numbers of intermediate diaphragms based on the evaluated stiffness ratio. Target bridges for this study were straight continuous span bridges with a single-cell steel box section. The parameters for the parametric study were the shape of box section, the span numbers, the equivalent span length, the stiffness of intermediate diaphragms, and the spacing of intermediate diaphragms. From the results of the parametric study, the effective spacing and numbers as well as the stiffness ratio of the intermediate diaphragms will be presented.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.3
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• pp.111-119
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• 2022

The increasing sectional stiffness and inducing prestress method of continuous steel box girder using modular CFT members use the restoring force of the CFT module generated from removing the prestressing bars in the CFT module after integrating the prestressed CFT module with the lower steel plate of the steel box girders as a prestressing force. The integrated CFT module in the steel box girder can improve the sectional stiffness of the continuous steel box girder section. To examine the applicability of the introduction of prestressing to the integrated steel box girder using the CFT module, in this study, inducing prestressing tests were conducted using CFT modules for steel plate specimens simulating the lower steel plate of the continuous steel box girder, and FE analyses were conducted for inducing prestressing tests. In addition, to confirm the effect of inducing prestress to the actual steel box girder and increasing sectional stiffness by the CFT modules, FE analyses for the actually applicable continuous steel box section were carried out depending on prestressing force and sectional conditions of the CFT modules, FE analysis results were compared.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.427-432
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• 2003

An analytical method to predict the flexural behavior of composite girder is presented in which the early-age properties of concrete are specified including maturing of elastic modulus, creep and shrinkage. The time dependent constitutive relation accounting for the early-age concrete properties is derived in an incremental format by expanding the total form of stress-strain relation by the first order Taylor series with respect to the reference time. The sectional analysis calculates the axial and curvature strains based on the force and moment equilibriums. The deflection curve of the box girder approximated by the quadratic polynomial function is calculated by applying to the proper boundary conditions in the consecutive segments. Numerical applications are made for the 3-span double composite steel box girders which is a composite bridge girder filled with concrete at the bottom of the steel box in the negative moment region. The one dimensional finite element analysis results are compared with those of the three dimensional finite element analysis and the analytical method based on the sectional analysis. Close agreement is observed among the three methods.

• Journal of Korean Society of Steel Construction
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• v.19 no.6
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• pp.681-693
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• 2007

Construction techniques for continuous steel bridges were applied to steel-concrete double composite box girder bridges. Concrete depth and length at the bottom of the steel box in the negative moment region were determined by plastic moment region and negative moment region of the double composite section, respectively. Construction methods, such as crane lifting method, free cantilever method, and incremental launching method were used for the analysis of the construction stage. Two cases of the construction phase were considered and analyzed for the stress resultant of double composite girders. The behavior of the nose-deck elastic system was examined by three-dimensionless parameters, such as the nose length, the unit weight of the launching nose, and the flexural stiffness of the nose. The adoption of the launching nose has become an effective solution in the incremental launching of steel-concrete double composite box girder bridges.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.165-166
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• 2009

This paper is to research for construction of the longest open toped steel box girder composite bridge using precast concrete deck in the country. This type bridge can bring down the construction costs by reducing the steel's weight used it's girders. And, it also can reduce working hours for construction over 6months by applying the precast deck system. I will introduce the process of construction the longest this type bridge within the country named Seochon Bridge

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.719-726
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• 2005

The optimal design was performed for the bridge superstructure composed of steel box girders and concrete deck considering life cycle cost. The service life of the superstructure was estimated, after load carry capacity curves for steel girder and concrete deck were derived on the basis of condition grade curves and maintenance histories. The object function was determined as life cycle cost, including initial cost, total maintenance cost, disposal cost and user cost, for a period of the estimated service life. The optimal design of the superstructure was performed for the various service lifes. The annual costs were used to compare calculated results and to get the most economical design. Also this paper presents reasonable idea for the use of user cost with uncertainty.

• Steel and Composite Structures
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• v.44 no.5
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• pp.619-632
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• 2022

There are numerous structural details (Longitudinal beam, web plate, U-ribs and I-ribs) in the top and bottom plates of steel box girders, which have significant influences on the longitudinal stress (normal stress) distribution. Clarifying the influence of these structural details on the normal stress distribution is important. In this paper, the ultra-wide steel box girder with large cantilevers of the Jinhai Bridge in China, which is the widest cable-stayed bridge in the world, has been analyzed. A 1:4.5 scale laboratory model of the steel box girder has been manufactured, and the influence of structural details on the normal stress distribution in the top and bottom plates for four different load cases has been analyzed in detail. Furthermore, a three-dimensional finite element model has been established to further investigate the influence regularity of structural details on the normal stress. The experimental and finite element analysis (FEA) results have shown that different structural details of the top and bottom plates have varying effects on the normal stress distribution. Notably, the U-ribs and I-ribs of the top and bottom plates introduce periodicity to the normal stress distribution. The period of the influence of U-ribs on the normal stress distribution is the sum of the single U-rib width and the U-rib spacing, and that of the influence of I-ribs on the normal stress distribution is equal to the spacing of the I-ribs. Furthermore, the same structural details but located at different positions, will have a different effect on the normal stress distribution.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.1
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• pp.11-20
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• 2004

The main goal of this study is to develop MATLAB programming for an analysis of distortional deformations and stresses of the straight box girder. For this purpose, a distortional deformation theory is firstly summarized and then a BEF (Beam on Elastic Foundation) theory is presented using analogy of the corresponding variables. Finally, with governing equations of the beam-column element on elastic foundation, an exact element stiffness matrix of the beam element and nodal forces equivalent to concentrated and distributed loads are evaluated via a generalized linear eigenvalue problem. In order to verify the efficiency and accuracy of this method, distortional stresses of box girders with multiple diaphragms are presented and compared with results by FEA.

• Journal of the Korea Concrete Institute
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• v.26 no.2
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• pp.109-116
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• 2014

The flexural behavior test of UHPC segmental box girder which has 160 MPa compressive strength and 15.4 m length was carried out. The effect of steel fibers in combination with reinforcing bars on improving the ductile performance of UHPC box girder was evaluated by comparing the flexural behavior of the UHPC segmental box girders made by the two kinds of mixing portion. The test variables are volume fraction of steel fibers and the arrangement of reinforcing bars. The behavior of UHPC box girder BF2 composed of 1% volume fraction of steel fibers and longitudinal reinforcing bars in web and upper flange with stirrup showed the similar ductile behavior with the girder BF1 composed of 2% volume fraction without stirrup in elastic stress region. But BF1 had the better stiffness and showed the more ductile behavior in inelastic stress region. Segmental interfaces of UHPC box girder have not any crack and slide until the final flexural collapse load.