Parametric study of curved steel I-girder bridges at construction phase.

The desire to conform to the existing terrain has largely increased the use of curved bridges for complex interchanges. Bridge curvature produces warping moments (lateral bending moments) in girder flanges under truck loading conditions and even during the construction phase. These warping moments increase girder flexural stresses at construction phase in case of un-shored construction. An extensive parametric study was conducted, using the finite-element analysis software "SAP2000", to examine the key parameters affecting warping stresses in curved girder bridges under construction loads. A strengthening technique "torsion box" at the girder supports was proposed and examined with respect to girder warping, flexural stresses and support reactions. The key parameters considered in this study included number of girders, girder spacing, number of cross bracing intervals, degree of curvature and girder span length. Based on this study empirical expressions for moment and shear distribution factors for the curved girder were developed.

Parametric study of curved steel I-girder bridges at construction phase.

The desire to conform to the existing terrain has largely increased the use of curved bridges for complex interchanges. Bridge curvature produces warping moments (lateral bending moments) in girder flanges under truck loading conditions and even during the construction phase. These warping moments increase girder flexural stresses at construction phase in case of un-shored construction. An extensive parametric study was conducted, using the finite-element analysis software "SAP2000", to examine the key parameters affecting warping stresses in curved girder bridges under construction loads. A strengthening technique "torsion box" at the girder supports was proposed and examined with respect to girder warping, flexural stresses and support reactions. The key parameters considered in this study included number of girders, girder spacing, number of cross bracing intervals, degree of curvature and girder span length. Based on this study empirical expressions for moment and shear distribution factors for the curved girder were developed.

Experimental study on shear behavior of curved box girders with corrugated steel webs

<p>Curved girder bridges with corrugated steel webs have already been constructed around the world; however, few works have been done on their shear behavior. To investigate the shear behavior of corrugated steel webs in curved girders, a curved box girder with corrugated steel webs was investigated and tested in current study. The method of three-point loading was used in the test. Test results indicate that the girder failed due to nonlinear shear buckling of the webs and the shear yield stress of the material was less than the elastic shear buckling stress of the corrugated steel webs. Failure of the corrugated steel webs was initiated by the local shear buckling of one of the corrugation panels, which propagated to other panels. In the failure stage, the interactive shear buckling occurred in outboard and inboard corrugated steel webs. In addition, many cracks appeared in the concrete top flange nearby the top supports and the concrete bottom flange between the 1/4 span to 3/4 span. The girder with corrugated steel webs can continue to resist the load after the occurrence of shear buckling. For the design of this type of curved box girder, it is necessary to consider the shear buckling of the corrugated steel webs.</p>