• Journal of Korean Society of Steel Construction
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• v.28 no.5
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• pp.365-371
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• 2016

In the case of the superstructure which is consist of two I girders and slab, the section can behave as II section, so that the neutral axis with respect to out of plane direction flexure can be regarded as major axis. Therefore in-plane flexural mode might govern the free vibration mode. Meanwhile, horizontally curved girders always experience not only bending moments but also torsional moments although the primary load is usually supposed to be gravitational load. The interaction due to bending and torsional moments make the behavior complicated and torsional mode may govern the free vibration mode. In other words, structure can have different dynamic characteristic due to its initial curvature. In this research, using 3-dimensional sell elements, free-vibration analyses are carried out due to initial curvature. The analysis models are assumed to be composite and non-composite and finally natural frequency and eigen mode are discussed.

• Journal of Korean Society of Steel Construction
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• v.21 no.4
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• pp.403-411
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• 2009

In the present study, nonlinear earthquake analysis was carried out for a steel girder bridge that had been damaged by the 1995 Kobe earthquake. For such analysis, the use of hysteretic models describing flexure-axial and shear-axial interaction was suggested. The models were incorporated into a structural analysis program in terms of the joint elements representing hinge models, and then a simplified analysis scheme using the hinge models was employed for bridge piers. The analytical predictions of the flexure-axial interactive hinge model show a good correlation with those of the detailed fiber element model. In addition, the analytical predictions of the flexure-shear-axial interactive hinge model enable a displacement component to be separately captured. It is thus recognized that the present study can be a useful scheme for the healthy evaluation of the global displacement performance of piers subjected to earthquake excitation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.6
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• pp.100-109
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• 2011

Recently, the concrete-steel hybrid extradosed bridge has been proposed as alternative bridge type at long span site. The hybrid extradosed bridge adopts light orthogonal deck girder instead of heavy concrete deck girder at the center span of bridge, and it enables to construct long-span bridge. And also, for this bridge type the decrease of self-weight of girder enables to reduce girder depth and side span length of extradosed bridge, so its type has more efficient structural behavior and makes it possible to perform optimal bridge design. Therefore, it is very important to set up the procedure and parameters of optimal design for concrete-steel hybrid extradosed bridge. In this study, the effects of design parameters (the variation of pylon height, bridge deck depth and orthogonal deck girder length) are discussed. And numerical analysis and sensitivity analysis are carried out according to these parameters. And design weight values about these parameters are quantitatively suggested to reflect characteristics of concrete-steel hybrid bridge.

• Journal of Korean Society of Steel Construction
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• v.12 no.2 s.45
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• pp.133-142
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• 2000

This study deals with behavior of steel box girder bridges according to the concrete slab casting sequences and sectional types. The time dependent behavior of bridges caused by the differential setting of slab concrete resulting from time gap for each part of slab deck in a sequential placing method produces is analyzed. In correlation studies between girder section types and placing sequences, time dependent effects of concrete creep and shrinkage are implemented in the analytical model proposed in the previous study. Finally, field recommendations in terms of concrete slump and relative humidity are suggested to prevent early transverse cracking of concrete slabs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2391-2400
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• 2015

Weather proof steels are used for steel bridges due to its high corrosion resistance under atmospheric conditions. However, instead of forming stabilized rust layers, general rust occurs on weather proof steels under high humidity condition close to seawater or shady places. In Japan, therefore, they perform rust stabilization treatment instead of unpainted treatment due to severe atmospheric conditions. However, most of domestic weather proof steels were constructed unpainted in the form of closed box-girder, which makes the periodical repetition of dry and wet hard to occur. For the steel bridges constructed on the Han river, the evaporation of water, dew condensation due to temperature change, and stagnant water due to rain affect harmfully on the formation of passive film on weather proof steels. Thus, in this research, in order to analyze corrosion properties inside the closed box-girder for the unpainted weather proof steel bridge in the waterworks safety zone, multiple ways of analysis such as observation with eyes, cellophane-tape test, steel thickness measurement, surface corrosion potential measurement, electron microscope analysis, and X-ray diffraction analysis of the rust were performed. As a result, unstable rust layer was observed inside the closed box-girder, and severe corrosion was observed on the top and bottom of the flanges due to the effects of stagnant water caused by rain, dew condensation, and de-icing materials.

• Journal of Korean Society of Steel Construction
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• v.18 no.6
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• pp.717-726
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• 2006

Traditional external post-tensioning method using either steel bars or tendons is commonly used as a retrofitting method for steel composite bridges. However, the method has some disadvantages such as stress concentration at anchorages and inefficient load-carrying capability of live loads. Multi-stepwise prestressing method using thermal expanded coverplate is a newly proposed prestressing method, which was originally developed for prestressing steel structures. A new retrofitting method for steel girder bridges founded on a simple concept of thermal expansion and contraction of cover plate, the method is a hybrid of and combines the advantages of external post-tensioning and thermal prestressing. In this paper, basic concepts of the method are presented and an illustrative experiment is introduced. From actual experimental data, the thermal prestressing effect was substantiated and the FEM approach for its analysis was verified. The retrofitting effects ofa single-span bridge were analyzed and the feasibility of the developed method was examined.

• Journal of Korean Society of Steel Construction
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• v.22 no.5
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• pp.411-420
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• 2010

In general, moving vehicles generate continuous and repetitive strain of energy on bridges. The strain energy can convert to electric energy due to its piezoelectric element. However, some factors should be considered in order to reasonably assess the feasibility such as load distribution applied on bridges and the relationship of strains generated according to loads. This study was carried out to estimate the generated voltage when piezoelectric elements were installed to a bridge. A steel-concrete composite specimen was fabricated and loads were applied, considering vehicle load-effects. As a result, the voltage generated in the element was evaluated and compared with the analysis equation of the piezoelectric effect.

• Journal of Korean Society of Steel Construction
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• v.18 no.3
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• pp.339-347
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• 2006

This study proposes a double-composite section to enhance the s serviceability of twin-girder railway bridges, especially in terms of the flexural stiffness of the composite section in negative-moment regions. This paper deals with experiments on continuous twin-girder bridge models with 5m-5m span length with the proposed double-composite action. From results of static tests on the bridge models, several design considerations were investigated including effective width, shear connection and ultimate strength of the double-composite concrete slab showed full shear connection, which verified the suggested empirical equation. From the flexural behavior of the double-composite section, the effective width of the bottom concrete slab can be evaluated as that of the concrete slab under compression. The ultimate flexural strength of the bridge models verified the validity of the rigid plastic analysis of the double-composite section. Design guidelines were suggested based on the test results.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.35-43
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• 2006

In this paper, procedures and research results involved in the development of glass reinforced composite bridge deck of hollow section were presented. Laminate design for the 3 cell deck section was performed. Structural characteristics such as serviceability, strength, failure and stability for DB24 load were analytically studied through the finite element analysis for the composite deck plate girder bridge. Composite deck tube was fabricated with pultrusion and extensive tests such as flexural test, girder-connection test, barrier-connection test, compression fatigue test and flexural fatigue test were carried out to evaluate structural behavior experimentally. Also, field load test was conducted for the demonstration plate girder bridge with composite deck and requirements for the strength and serviceability were reviewed.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.137-140
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• 2008

Minimizing the girder number and appling the long span deck of plate girder bridge is the main factors in the practical and economic design of the Twin Steel Girder Bridge. Therefore, it is important to verify the ability of the long span concrete deck. In this paper, to improve the problem, the precast concrete full depth deck has been used instead of cast-in-place concrete deck. The precast concrete full depth deck having longitudinal and transverse prestress is efficient to design of the long span concrete slabs. This paper introduces the design concept of Twin Steel Bridge using the precast concrete full depth deck and applied design case.