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Influence of staggered cross-frame layout on the behavior of horizontally-curved steel I-girder bridges
Journal
Proceedings of the Annual Stability Conference Structural Stability Research Council, SSRC 2024
Date Issued
2024-01-01
Abstract
Cross-frames are typically provided contiguously in the radial direction in horizontally curved I-girder systems. The radial arrangement of cross-frames results in larger unbraced lengths in the outermost girder and smaller unbraced lengths in the innermost girder. Because cross-frames act as primary load-carrying members in curved girder bridges, altering cross-frame layouts can improve load distribution between girders. This paper investigates the effects of providing a staggered cross-frame layout on the behavior of a single-span horizontally curved steel I-girder bridge during construction. A staggered cross-frame arrangement, which is observed to be advantageous in skewed I-girder bridges, is similarly examined here for curved I-girder bridges. These studies compare deflections, web rotations, cross-frame stresses, and bottom flange stresses for staggered cross-frame layouts with those from a radial contiguous layout using finite element analyses. Results indicate that a staggered cross-frame layout provides nearly the same buckling strength as a radial layout. However, increased web rotations and deflections in the outer girders and reduced web rotations in the inner girders are observed. Additionally, cross-frame normal stresses decrease slightly. The studies suggest that a strategically selected combination of radial and staggered cross-frame layouts can result in an overall improvement across design parameters.