Abstract
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.
Highlights
Curved steel !-girders are frequently used in complex interchanges in today's congested urban areas due to high real state cost, alignment restrictions and excellent serviceability
A similar trend can be predicted when increasing the girder spacing with the same number of girders since the bridge width increases
Available empirical equations for minimum number of cross-bracing intervals to limit warping stresses in curved girders were examined in this study
Summary
Curved steel !-girders are frequently used in complex interchanges in today's congested urban areas due to high real state cost, alignment restrictions and excellent serviceability They allow a -smooth traffic flow and eliminate the right of way creating a painless directional transition at interchanges. Nowadays it become possible to design curved bridges with much greater spans because of available technology for design and fabrication while in the early days of curved bridge design and construction, bridge superstructures supporting curved roadway alignment were comprised of short straight girders linked at the supports. This resulted in inefficient use of very short spans between support piers.
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