• Journal of the Korea Concrete Institute
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• v.27 no.2
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• pp.185-193
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• 2015

Ultra high performance concrete (UHPC) has been developed to overcome the low tensile strengths and brittleness of conventional concrete. Considering that UHPC, owing to its composition and the use of steel fibers, develops a compressive strength of 180 MPa as well as high stiffness, the top flange of the steel girder may be superfluous in the composite beam combining a slab made of UHPC and the steel girder. In such composite beam, the steel girder takes the form of an inverted-T shaped structure without top flange in which the studs needed for the composition of the steel girder with the UHPC slab are disposed in the web of the steel girder. This study investigates experimentally and analytically the flexural behavior of this new type of composite beam to propose details like stud spacing and slab thickness for further design recommendations. To that goal, eight composite beams with varying stud spacing and slab thickness were fabricated and tested. The test results indicated that stud spacing running from 100 mm to 2 to 3 times the slab thickness can be recommended. In view of the relative characteristic slip limit of Eurocode-4, the results showed that the composite beam developed ductile behavior. Moreover, except for the members with thin slab and large stud spacing, most of the specimens exhibited results different to those predicted by AASHTO LRFD and Eurocode-4 because of the high performance developed by UHPC.

• Journal of the Korea Concrete Institute
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• v.14 no.4
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• pp.503-512
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• 2002

Generally, the girder spacing of the two-girder composite bridge is from 5m up to 15m. To ensure the structural safety according to Korean Bridge Design Specification, the deck depth should be from 33 cm upto 73 cm. Using the transversal prestressing strands in concrete deck, we can reduce its depth about 10％. However, there is little experience on the design and construction of prestressed concrete(PSC) decks in Korea. This paper focuses on the behaviors of PSC deck. A literature survey is performed widely. Considering the characteristics of the two-girder bridge and the construction conditions in Korea, a cast-in-place PSC deck is recommended for the two-girder bridge with 6m girder spacing. To examine its structural behaviors and safety, three partial model deck specimens(3 m$\times$5 m) with real scale are fabricated md tested. One(PS34-RS) is 34cm depth with the stiffness restraint in longitudinal edges for simulating the real bridge deck. Another(PS34-NS) is same depth without the stiffness restraint, and the other(PS28-NS) is 28cm depth with the stiffness restraint. Under the static patch loading, each specimen had a larger ultimate flexural strength than the design value. Specimens with the stiffness restraint (PS34-RS and PS28-RS) showed the punching shear failure mode and specimen without that(PS34-NS) showed the flexural failure mode.

• Journal of Korean Society of Steel Construction
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• v.20 no.2
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• pp.227-236
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• 2008

The kind of concrete generally used in steel concrete composite bridges is normal-weight concrete whose unit weight is ${2,300kg/m^{3}}$. However, using lightweight concrete in composite bridges diminishes the sectional forces due to the self-weight of concrete decks. As a result, this will make the bridge design more economical. The type of concrete deck that could be adopted in composite bridges using lightweight con crete may be classified into Cast-In-Place (C.I.P.) concrete deck and precast concrete deck. These two types of decks have some differences with respect to structural behavior and constructional method, and hence,structural behavior of stud shear connectors that connect a concrete deck to a steel girder is changed with the type of deck used. In this study, push-out tests were conducted to evaluate the characteristics of static behavior of the stud shear connectors with a precast deck using lightweight concrete. Also, additional precast deck specimens with bedding layer that had shear keys and devices for transverse confinement of the bedding layer for the prevention of cracks occurring in the bedding layer were tested. These cracks The efficiency of these devices was then evaluated.

• 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.

• Journal of Korean Society of Steel Construction
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• v.22 no.5
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• pp.465-475
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• 2010

In the horizontally curved bridges, girders are subjected to the combined action of vertical bending and torsion due to their curvatures without any eccentric loads. As subjected to bending and torsion, the ultimate strength of steel/concrete composite box girders are limited by the diagonal tensile stress in the deck concrete induced by the St. Venant torsion. To determine the ultimate strength of composite box girders in bending and torsion and their interactions, this study conducted a 3-dimensional FEA and classical strength of materials investigation. Using ABAQUS, the FEA fully utilized advanced nonlinear analysis techniques simulating material/geometrical nonlinearity and post-cracking behaviors. The ultimate strength from numerical data were compared with theoretically derived values. Concurrent compressive stresses in the concrete deck improve the shear-resisting capacity of concrete, thereby resulting in an increased torsional resistance of the composite box girder in positive bending. The proposed interaction equation is very simple yet it provides a rational lower bound in determining the ultimate strength of concrete/steel composite box girders.

• Steel and Composite Structures
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• v.4 no.5
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• pp.385-402
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• 2004

Nearly 400 composite railway bridge decks of a new kind belonging to the trough type with U-shaped cross section have been constructed in Belgium over the last fifteen years. The construction of these bridge decks is rather complex with the preflexion of precambered steel girders, the prestressing of a concrete slab and the addition of a 2nd phase concrete. Until now, they have been designed with a classical computation method using a pseudo-elastic analysis with modular ratios. Globally, they perform according to the expectations but variability has been observed between the measured and the computed camber of these bridge decks just after the transfer of prestressing and also at long-term. A statistical analysis of the variability of the relative difference between the measured camber and the computed camber is made for a sample of 36 bridge decks using no less than 10 variables. The most significant variables to explain this variability at prestressing are the ratio between the maximum tensile stress reached in the steel girders during the preflexion and the yield strength and the type of steel girder. For the same sample, the long-term camber under permanent loading is computed by two methods and compared with measurements taken one or two years after the construction. The camber computed by the step-by-step method shows a better agreement with the measured camber than the camber computed by the classical method. The purpose of the paper is to report on the statistical analysis which was used to determine the most significant parameters to consider in the modeling in order to improve the prediction of the behaviour of these composite railway bridge decks.

• Journal of the Korea Concrete Institute
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• v.26 no.2
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• pp.151-157
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• 2014

Since recently developed Ultra-High-Performance-Concrete (UHPC) provides very high strength, stiffness, and durability, many studies have been made on the application of the UHPC to bridge decks. Due to high strength and stiffness of UHPC bridge deck, the structural contribution of top flange of steel girder composite to UHPC deck would be much lower than that of conventional concrete deck. At this point of view, this study proposes a inverted-T shaped steel girder composite to UHPC deck. This girder requires a new type of shear connector because conventional shear connectors are welded on top flange. This study also proposes three different types of shear connectors, and evaluate their ultimate strength via push-out static test. The first one is a stud shear connector welded directly to the web of the girder in the transverse direction. The second one is a puzzle-strip type shear connector developed by the European Commission, and the last one is the combination of the stud and the puzzle-strip shear connectors. Experimental results showed that the ultimate strength of the transverse stud was 26% larger than that given in the AASHTO LRFD Bridge Design Specifications, but a splitting crack observed in the UHPC deck was so severe that another measure needs to be developed to prevent the splitting crack. The ultimate strength of the puzzle-strip specimen was 40% larger than that evaluated by the equation of European Commission. The specimens combined with stud and puzzle-strip shear connectors provided less strength than arithmetical sum of those. Based on the experimental observations, there appears to be no advantage of combining transverse stud and puzzle-strip shear connectors.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2814-2820
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• 2011

Railway bridge, contact of vehicle needs to design considering the running safety about the running train load of the railway bridge, ride comfort and dynamic safety. Also, upper structure of the railway bridge has to satisfy design standard about moving load(train). So, the railway bridge has to satisfy the requirement for vertical acceleration of the bridge deck, vertical displacement of the bridge and face distortion, which is suggested railway design standard in Korea(2011.5.). In this study, it was investigated and evaluated to the running safety about the running train load of the railway bridge, ride comfort and dynamic safety with railway design standard for steel composite(Steel Box Girder) railway bridge considering KTX, freight train and standard train load.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.6
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• pp.1537-1542
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• 2007

In this study, based on a I-roll embedded steel composite deck, it is suggested a new type of simplified composite deck and analyzed under construction loading. Using ABAQUS, it's estimated effects of welding amount of steel plate and I-section, existence of a hole of I-section's flange, and a location of hole. For a reasonable verification of modeling, compare Euler-Beam theory with F.E.M models. In result, it is verified that change of welding amount increase more maximum bending tension stresses at the central part's section of span when elements are partial-welded. Also, verify that deflection is slightly increased when a hole existed compared with no hole.

• Steel and Composite Structures
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• v.52 no.2
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• pp.237-248
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• 2024

In order to make the dynamic analysis and design of improved composite beam with corrugated steel web (CBGSCC) bridge more efficient and economical, the parametric self-cyclic analysis model (SCAM) was written in Python on Anaconda platform. The SCAM can call ABAQUS finite element software to realize automatic modeling and dynamic analysis. For the CBGSCC bridge, parameters were set according to the general value range of CBGSCC bridge parameters in actual engineering, the SCAM was used to calculate the large sample model generated by parameter coupling, the optimal value range of each parameter was determined, and the sensitivity of the parameters was analyzed. The number of diaphragms effects weakly on the dynamic characteristics. The deck thickness has the greatest influence on frequency, which decreases as the deck thickness increases, and the deck thickness should be 20-25 cm. The vibration frequency increases with the increase of the bottom plate thickness, the web thickness, and the web height, the bottom plate thickness should be 17-23mm, the web thickness should be 13-17 mm, and the web height should be 1.65-1.7 5 m. Web inclination and Skew Angle should not exceed 30°, and the number of diaphragms should be 3-5 pieces. This method can be used as a new method for structural dynamic analysis, and the importance degree and optimal value range of each parameter of CBGSCC bridge can be used as a reference in the design process.