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Project Type
Emerging Investigators Program
Project Dates
06/01/2015 - 08/31/2016
Principal Investigators
Project Status

Skew of the supports in steel I-girder bridges cause undesirable torsional effects, increased cross-frame forces, and generally increase the difficulty of designing and constructing a bridge. The girders experience differential deflections due to the skew supports, and the undesirable effects arise when the girders are linked transversely. Before the placement of the deck, the main method of linking the girders transversely is through the use of cross-frames. The cross-frames are designed to provide stability during construction and distribute transverse loads through the bridge girders; this is their primary role. Cross-frames also help control differential displacement during deck placement and distribute vertical loads in the bridge’s elastic and inelastic ranges. The cross-frames are not specifically designed for these tasks; these are the secondary role of the cross-frames. Alternative cross-frame designs, such as lean-on bracing, have been proposed to reduce the effects of skew due to the cross-frames. While having been show to improve skew effects, the alternative cross-frame designs have not been evaluated on the effect they have on the cross-frames secondary roles.