Instrumentation and Load Rating of Steel Curved Girder Bridges

Curved girder bridges are frequently used by state departments of transportation because they add significant flexibility in the determination of highway alignments, especially at congested interchanges. Much of the seminal research into the behavior of curved girder bridges was conducted in the late 1960s. The development of computer programs for the analysis and design of curved-girder bridges quickly followed and they have become more advanced over time. While the load path for a straight girder bridge is such that the girders are subjected primarily to shear forces and strong-axis bending moments, the load path in curved girders bridges inherently includes eccentric loads that result not only in strong axis shear forces and bending moments but also torsional moments, warping, and the resulting shear. As a result, the level of complexity in modeling a curved bridge is increased exponentially when compared to a straight bridge. A secondary consideration is the selection of girder configurations for curved-girder bridges. While I-shaped girders are often selected as the de facto section of choice for straight bridges, box girders offer significant advantages over I-shaped girders in curved bridges because of the relatively high torsional rigidity that they offer. This article addresses the most significant issues involved with the analysis and design of curved girder bridges starting with a review of the mechanics associated with torsion, which acts on the members, moving into a review of research conducted to date, which is then followed by a summary of design provisions. Next, the topic of finite element modeling of curved girder bridges in 2D and 3D will be addressed. Finally, a discussion of evaluation and load rating of curved bridges will be presented. As a final consideration, a study comparing the behavior of tangent bridges (bridges made up of straight girders supporting a horizontally curved roadway) with the behavior of curved bridges will be conducted and included in the thesis. Advisors/Committee Members: Swanson, James.