The Shear Loading Capacity and Behavior of Horizontally Curved Steel I-girder Bridges, and the Imperfection Effect

In this study, horizontally curved steel I-girder bridges having various radii of curvatures in practical dimensions, and designed via the AASHTO standards are modeled and analyzed via the finite element software ABAQUS. The aim of these material-geometric non-linear analyses are to characterize the shear behavior, the shear failure mechanism and the shear resistance of steel I-girders in the complete bridge systems and in their equivalent single girders. Results demonstrated that the shear behavior, the ultimate shear resistance, the shear buckling resistance of single-girders and bridge system are similar; whereas the initial stiffness of the two approaches differ. Furthermore, the equivalent single-girders are incapable of predicting the correct mechanism of the shear failure in some interior panels of the bridge system; due to the negligencs of the true horizontal and vertical stiffness of cross-frames, and also due to the interaction of girders. In addition, it is shown that under a specified geometric imperfection pattern, the ultimate shear resistance of curved I-girders is insensitive to the imperfection magnitudes; whereas, the ultimate shear resistance of straight I-girders reduces with the increase of imperfection magnitudes. The AASHTO provisions however, do not require the consideration of geometric imperfections on the ultimate shear resistance of I-girders.