• Earthquakes and Structures
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• v.11 no.4
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• pp.681-699
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• 2016

Steel box girders have two webs and two flanges on top that are usually connected with shear connectors to the concrete deck and are also known as tub girders. The end diaphragms of such bridges comprise of a stiffened steel plate welded to the inside of the girder at each end. The diaphragms play a major role in transferring vertical and lateral loads to the bearings and substructure. A review of literature shows that the cyclic behavior of diaphragms under earthquake loading has not been studied previously. This paper uses a nonlinear finite element model to study the behavior of the end diaphragms under gravity and seismic loads. Different bearing device and stiffener configurations have been considered. Affected areas of the diaphragm are distinguished.

• Journal of Korean Society of Steel Construction
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• v.24 no.2
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• pp.175-188
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• 2012

A parametric study for varying the radii of curvature is performed with a curved tub girder bridge having three continuous spans. The bracing forces of top lateral bracings from the results of numerical equations are compared to those of 3-dimensional finite element analyses. New modifying factors applicable in computing the nominal member forces of top lateral bracings were suggested. The numerical equations were derived based on one girder system, and it is shown that the numerical equations exhibit some errors compared with 3D FEA results. The main reason for this phenomenon lies on the number of girders. The twin girder system has an external cross-beam between inner and outer girder. It also has larger lateral stiffness than the single girder system. Finally, the distributions by the torsion, bending, distortion, and lateral loading of the top lateral bracing forces were presented in this paper.

• Journal of Korean Society of Steel Construction
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• v.23 no.2
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• pp.249-259
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• 2011

In this study, the distortional behaviors of tub-section steel girders subjected to torsional loading were analyzed, and predictor equations were developed for estimating the member forces induced in the internal bracing system installed in the steel tub girders. Torsional loadings originated either by eccentric vertical loading or girder curvature were decomposed into the pure torsional force component that does not affect the distortional box deformation, and into the distortional force component that directly induces box distortion. The axial member forces induced in the internal cross frames were formulated as a function of the magnitude of torsional loading through the analytical investigation of the interactions between the distortional force component and internal cross frames. To verify the proposed equations, three-dimensional finite element analysis (3D FEA) was conducted for the straight simple-span girder and the three-span continuous girder samples. Very good agreement was found between the member forces from the FEA and the proposed equations.

• 한국방재학회:학술대회논문집
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• 2009.02b
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• pp.106.1-106.1
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• 2009