• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.04a
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• pp.313-321
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• 1999

To design steel box girder bridge, designers have taken the classical load distribution coefficient methods. Due to the rapidly developing computer technique, steel box girder bridge is simply modeled as grillage method for analyzing the girder, or as fully finite element method for more accurate and detailed analysis. Recently, cruciform space frame method is developed for modeling and analyzing it more simply and easily compared with finite element method. So, this study for the examination of upper methods' characteristics loaded unit moment load and analyzed the distortional deflection with shell element method and cruciform space frame method, and for three span three girder steel box bridge, loading DB-24 loads, analyzed it by upper methods and compared the results.

• Journal of Korean Society of Steel Construction
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• v.12 no.5 s.48
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• pp.475-485
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• 2000

In this study, an automated optimum design program for steel box girder bridges has been developed for the optimum design of composite steel box girder bridges. The design constraints required for the optimum design of steel box girder bridges are based on the Korean standard bridge specification. Considering characteristics of steel box girder bridges, several approximation techniques, such as artificial constraint deletion, variable linking and stress reanalysis technique etc. are also introduced to enhance the efficiency of optimization. The developed program is mainly composed of major sub-system modules including structural analysis module using commercial structural analysis program such as RM-SPACEFRAME, optimum design module, pre-process module for friendly user input, and post-processor module for office automation. In addition, in order to demonstrate the efficiency and applicability of the developed optimum design program for steel box girder bridges, a few numerical examples are applied. Based on the results of the application, it may be stated that the automatic optimum design program developed in this study can be a prototype model for the developement of optimum design program for other type of bridge.

• 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.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.2
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• pp.88-97
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• 2011

For Korean design provisions are not equipped for skewed steel box girder bridges, when American provisions are adopted, load distribution factors different from real behavior are determinated. Furthermore the possibility of over or under estimated bridge design involves. The aim of this study is to provide more rational load distribution factor formulas based on real behavior for shear at obtuse corner of skewed steel box girder bridges. In order to accomplish the aim finite element analysis for a variety of skewed steel box girder bridge structural models is carried out, and each parameters degree of influence on wheel load distribution factors of skewed steel box girder bridges are analyzed. Then multiple regression analysis is fulfilled in order to propose formulas for determinating shear force load distribution factor of skewed steel box girder bridges.

• Journal of Navigation and Port Research
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• v.27 no.2
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• pp.199-207
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• 2003

In the combat environments at the sea, the naval ships should have enough structural integrity to perform the task under the enemy's attack and possible damages. Although the naval ships can be damaged from the enemy's attack, those damages should be minimized and the naval ships must maintain their combat capabilities continuously after recoveries from the damages. Therefore, it is ve교 important for modem naval ships, especially combat naval ships, to ensure the survivability. This paper reviewed the developing procedure for the technique of the naval ships structures and described method, especially box girder system considering survivability. The efficiency of box girder is examined by numerical simulation, and it is found that the establishment of box girder is a good design method to improve the survivability.

• Journal of Korean Society of Steel Construction
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• v.17 no.6 s.79
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• pp.649-660
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• 2005

Since the diaphragm manhole of steel box girder bridges is designed generally from experience, it has become the primary factor in the excessive cost of steel bridge construction. For the economical and efficient manufacture of diaphragm manholes, it is necessary to study the exact behavior of the diaphragm manhole in a steel box girder bridge. In this study, both an experimental test and a structural analysis are performed to verify the behavior of the diaphragm manhole in a steel box girder bridge. A detailed structural analysis was performed according to various diaphragm manhole shapes, and in conclusion, the suitable reinforcement method for the support of diaphragm manholes in steel box bridges is presented.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.235-242
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• 2001

An optimization algoriam for the optimum design of prestressed concrete (PSC) box girder bridges is proposed in this paper. In order to optimize the tendon profile efficiently, a reduced basis technique is introduced. The optimization algorithm which includes the tendon profile, tendon size and concrete dimensions optimization problem of the PSC box girder bridges is verified on the Genetic algorikhm (GA) from the numerical examples. it may be positively stated that the optimum design of the PSC box girder bridges based on the new approach proposed in this study will lead to more rational and economical design compared with the currently available designs.

• Steel and Composite Structures
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• v.17 no.5
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• pp.705-719
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• 2014

Composite steel-concrete box girders are frequently used in bridge construction for their economic and structural advantages. An integrated metaheuristic based optimization procedure is proposed for discrete size optimization of straight multi-span steel box girders with the objective of minimizing the self-weight of girder. The metaheuristic algorithm of choice is the Cuckoo Search (CS) algorithm. The optimum design of a box girder is characterized by geometry, serviceability and ultimate limit states specified by the American Association of State Highway and Transportation Officials (AASHTO). Size optimization of a practical design example investigates the efficiency of this optimization approach and leads to around 15% of saving in material.

• Structural Engineering and Mechanics
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• v.21 no.3
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• pp.275-293
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• 2005

When a thin-walled multicell box girder is subjected to an eccentric load, the distortion becomes an important global response in addition to flexure and torsion. The three global responses appear in a combined form when a conventional shell element is used thus it is not an easy task to examine the three global responses separately. This study is to propose an analysis method using conventional shell element in which the three global responses can be separately decomposed. The force decomposition method which was designed for a single-cell box girder by Nakai and Yoo is expanded herein to multicell box girders. The eccentric load is decomposed in the expanded method into flexural, torsional, and multimode distortional forces by using the force equilibrium. From the force decomposition, the combined global responses of multicell box girders can be resolved into separate responses and the distortional response which is of primary concern herein can be obtained separately. It is shown from a series of extensive comparative studies using three box girder bridge models that the expanded method produces accurate decomposed results. Noting that the separate consideration of individual global response is of paramount importance for optimized multicell box girder design, it can be said that the proposed expanded method is extremely useful for practicing engineers.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.479-482
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• 2005

The concrete box girder members are extensively used as a superstructure in bridge construction. The load carrying capacity of concrete box girders in lateral direction is generally influenced by the sizes of haunch and web. The internal upper decks are restrained by the webs and exhibit strength enhancement due to the development of aching action. The current codes do not have generally consider the arching action of deck slab in the design because of complexity of the behavior. However, there are significant benefits in utilizing the effects of arching action in the design of concrete members. The main objective of this paper is to propose a rational method to predict the ultimate load of deck slab by considering various haunch sizes and web restraint effect of concrete box girder bridges. To this end, a comprehensive experimental program has been set up and seven large-scale concrete box girders have been tested. A transverse analysis model of concrete box girders with haunches is proposed and compared with test data. The results of present study indicate that the ultimate strength is significantly affected by haunch dimension. The increase of strength due to concrete arcing action is reduced with an increase of prestressing steel ratio in laterally prestressed concrete box girders and increases with a larger haunch dimension. The proposed theory allows more realistic prediction of lateral ultimate strength for rational design of actual concrete box girder bridges.