• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.5A
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• pp.407-415
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• 2010

In Korea, more than 90% of the total number of steel bridges built for 40~70 m span length is a steel box-girder bridge type. A steel box-girder bridge is suitable for long span or curved bridges with outstanding flexural and torsional rigidity as well as good constructability and safety. However, a steel box-girder bridge is uneconomical, requiring many secondary members and workmanship such as stiffeners and ribs requiring welding attachments to flanges or webs. Therefore, in US and Japan, a plate girder bridge, which is relatively cheap and easy to construct is generally used. One type of the plate girder bridge is the two- or three-main girder plate bridge, which is a composite plate girder bridge that minimizes the number of required main girders by increasing the distance between the adjacent girders. Also, for the simplification of girder section, the stiffener which requires attachment to the web is not required. The two-main steel girder plate bridge is a representative type of plate girder bridges, which is suitable for bridges with 10 m effective width and has been developed in the early 1960s in France. To ensure greater safety of two- or three-main girder plate bridges, a larger steel section is used in the bridge domestically than in Europe or Japan. Also, the total number of two- or three-main girder plate bridge constructed in Korea is significantly less than the steel box girder bridge due to a lack of designers' familiarity with more complex design detailing of the bridge compare to that of a steel box girder bridge design. In this study, a new construction method called Turn Over method is proposed to minimize the steel section size used in a two- or three-main girder plate bridge by applying prestressing force to the member using confining concrete section's weight to reduce construction cost. Also, a full scale 20 m Turn Over girder specimen and a Turn Over girder bridge specimen were tested to evaluate constructability and structural safety of the members constructed using Turn Over process.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.1
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• pp.67-73
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• 2017

This study has addressed to evaluate the effects of radius of curvature and skew angle on the negative reaction in a plate girder bridge with LRB (Lead Rubber Bearing) supports. As analytical parameters, various radius of curvatures and skew angles were selected and two seismic loads of El-Centro and artificial earthquakes were applied to the bridge in the longitudinal and transverse directions. As results of 3D analysis, the possibility of negative reaction is shown at the part of acute angle and inner side of the curved bridge, and becomes increased when seismic load is applied in the transverse direction. In addition, the occurrence of negative reaction is found to be increased as both radius of curvature and skew angle decrease, which means that curved bridge has higher possibility of negative reaction than straight one. Conclusively, all of earthquake wave, gradient, radius of curvature and skew angle should be considered together to investigate the possibility of negative reaction at the bridge support subject to seismic load.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3A
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• pp.367-373
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• 2008

In the design of horizontally curved plate girder web panels, it is required to evaluate accurately the elastic buckling strength under pure shear. Currently, elastic shear buckling coefficients of curved web panels stiffened by transverse intermediate stiffeners are determined by assuming conservatively that straight web panels without curvature are simply supported at the juncture between the flange and web. However, depending upon the geometry and the properties of the curved plate girder, the elastically restrained support may behave rather closer to a fixed support. The buckling strength of curved girder web is much greater (maximum 38%) than that of a straight girder calculated under the assumption that all four edges are simply supported in Lee and Yoo (1999). In the present study, a series of numerical analyses based on a 3D finite element modeling is carried out to investigate the effects of geometric parameters on both the boundary condition at the juncture and the horizontal curvature of web panel, and the resulting data are quantified in a simple design equation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.3
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• pp.49-57
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• 2016

This study intended to analyze reinforcement effects of PSC I girder bridges to which prestresses are introduced using V type of external strands. So that series of bridge loading tests are carried out on existing PSC I girder bridge for the cases of before-reinforcement and reinforcement. The measured results from tests being analyzed and compared with the ones from MIDAS structural analyzing program, the reinforcing effects of the reinforcement system adopted in this study were investigated. It is found out that when the V type systems are applied to the bridge girders, the slope of load distribution factor curves become lower improving soundness of bridge upper structure. And also it is confirmed that the reinforcement system in this study can be taken as helpful for improvement of both flexural and shear ability of PSC I girder bridges, as well as dynamic behavior. Furthermore it is found when the elastic pads are applied to the system, dynamic reinforcing effects are maximized.

• Journal of Korean Society of Steel Construction
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• v.17 no.5 s.78
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• pp.511-518
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• 2005

The behavior of steel curved bridges is more complicated than straight bridges, thus the analysis, design and construction process of curved bridges require much more attention. In design of curved bridges, the grillage analysis using general structural analysis program or special program is mainly used. Comparative study in coherence between these analytical results and actual behavior of curved bridges has been rarely conducted. To study the behaviour of curved bridges and verify the current design method, field measurements and analyses using general structural analysis program and 3-D refined analysis program were carried out for simple and continuous bridges in this study. The study focused on the behavior of curved steel bridges during construction. Measured and analytical results had quantitative difference mutually, but there were qualitatively similar. Stress variations in transverse direction of flange were observed and grillage analysis models yielded more conservative values than 3-D refined analysis models.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.4
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• pp.109-120
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• 2003

The state-of-art of curved box girder bridge with cross section design has advanced in various area. In these days, several analytical techniques for behaviors of curved box girder bridges cross section are available to engineers. The transfer matrix method is extensively used for the structural analysis because its merit in the theoretical background and applicability. The technique is attractive for implementation on a numerical solution by means of a computer program coded in Fortran language with a few elements. To demonstrate this fact, it gives good results which compare well with finite element method. Therefore, this paper proposed the static analysis method of curved box bridge with cross section by transfer matrix method based on pure-torsional theory and the optimal span ratio/variable cross section ratio of 3 span continuous curved box girder bridge.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.1
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• pp.9-14
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• 2008

In the case of horizontally curved bridges, the use of curved composite box girder bridges are increased due to its functionality and for aesthetical reason. As it compared with the open section, the steel box girder bridges have advantages to resistant of distortion and corrosion. In practice the grid analysis is conducted by utilizing only the cross beam. Since the stiffness of the concrete slab is not included in the grid analysis, the cross beam is induced the distribution of the live load. In this study the affects of the radius of curvature, the number of diaphragm and cross beam to the load distribution of the curved steel box girder bridge was investigated by applying the finite element method. The results indicate that the curvature of curved bridge had a large affect of the load distribution and as the curvature was increased the load distribution factor was increased. A single diaphragm at the center of girder is important role for the load distribution effects and structural stability, but additional diaphragm did not affect it as much. The affects of the cross beam to the load distribution were investigated and its influence was minor. It can be safely concluded that the addition of cross beam does not aid the purpose of the live load distribution. And the stiffness of concrete slab for the load distribution effects should be concerned in the design of curved steel box girder bridges.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.1
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• pp.205-215
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• 2006

In this study 3-D shell FEM model was applied to analyze the behavior of curved steel box girders stiffened by diaphragms. The reliability of the analytical method has been proved by comparing with the existing results. It was also found from this analysis that main factors affecting a distortional stress are length of a girder, curvature of the girder, and spacing of diaphragms. A modelled bridge with 30m of span length and 40m of radius was analyzed to find an optimum spacing of diaphragm, and as a result of applying different spacings, 5m was found to be most appropriate to control the stress ratio regulated by specifications. In the effect of diaphragm shape, the rhamen-typed diaphragm is found to be more effective than the fully filled-up one in the range of opening ratio of 0.4 to 0.6. But, the fully filled-up diaphragm had more efficiency in terms of reducing the distortional stress than X-truss typed diaphragm.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.269-272
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• 2008

The seismic fragility curves of a structure represents the probability of exceeding the prescribed structural damage given various levels of ground motion intensityand the seismic fragility curve is essential to evaluation of structural performance and assessment of risk and loss of structures. The purpose of this paper is to develop seismic fragility functions for bridge structures in Koreaby reviewing those of advanced countries. Therefore, at first, we investigated development conditions of the seismic fragility functions. And the next highway bridges in Korea are classified into a number of categories and several typical bridges are selected to estimate seismic fragilities for using this analysis method in Korea. Finally, fragility curves for PSC Box girder bridge are estimated. The results show that the bridge classification and damage state play an important role in estimation of seismic damage and seismic fragility analysis for bridge structures.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.20-27
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• 2005

Solar radiation causes non-uniform temperature distribution in the structure, depending on the shape of the structure and its shadows. Especially in cases of curved steel box girder bridges, non-uniform temperature distribution due to solar radiation can reduce bridge life and serviceability when combined with another load combination. In this study, the method for predicting the temperature distribution of curved bridges developed by Kim et al., was used to predict the non-uniform temperature distribution which served as a basis for structural analysis of 3-D bridge behavior. In order to seek the most unfavorable conditions of solar radiation, observation data from the Korea Meteorological Administration for solar radiation were analyzed. The region of the most high solar radiation condition was selected and its one year variation of the solar radiation data was considered. From this analysis, the most unfavorable solar radiation condition with lower solar altitude and intense solar radiation was selected. Based on the selected solar radiation condition, structural behavior of curved bridges with diverse bridge direction, span length, radius and support conditions are analyzed.