Effects of external bracing on horizontally curved box girder bridges during construction

In horizontally curved steel box girder bridges, large relative displacements between box girders and individual girder rotations may occur during the deck pouring operation. Installing intermediate external cross-frames between box girders is perceived to be an effective means to control these displacements. However, it is imperative to minimize the number of such cross-frames, as these external cross-frames are not only expensive but also have adverse consequences for the fatigue characteristics of the steel box girders.A new parameter, deck unevenness ratio, was defined in this study to quantify the degree of uneven deck caused by relative deflections and rotations. In order to assess the effects of external cross-frames on the deck unevenness ratio that affect deck slab construction, a number of hypothetical twin-box girder bridges were analyzed for this study using a commercial finite element program, ABAQUS. The conventional method and Wisconsin DOT deck pouring sequences were compared for three-span continuous curved bridges.