Analysis of Horizontally Curved Bridges Using Simple Finite-Element Models

A series of horizontally curved bridges were analyzed using simple finite-element models. The analyses included using a typical truckload and also the dead load as the primary forces on bridges. In each analysis, the behavior of bridges was investigated, and the major internal forces developed in members were determined. Specifically, an increase in bending moment and the existence of a torsional moment in cases where the horizontal angle of curvature is large (about 20–30°) was observed. The significance of these moments, compared with the maximum bending moment of a comparable straight bridge, was noted. Bridges used in the analysis were assumed to be composed of single spans with about $30.5\text{-}\mathrm{m}$ (100-ft) span lengths (the chord length was set at 30.5-m for all bridges), steel girders, and an 203-mm (8-in.) reinforced concrete slab. The finite-element analyses consisted of a three-dimensional idealization using simple beam elements to model top and bottom flanges of the girders and plate bending elements modeling the girder webs and the slabs. The analyses revealed that this simple modeling could effectively be used in analyzing curved bridges. The analyses showed that the bending moment in girders of a curved bridge can be about 23.5% higher compared with moments in girders of a straight bridge of similar span and design configuration. As a result of the curved geometry of the bridge, a torsional moment is developed in the girders. The magnitude of this moment was found to be about 10.3% of the maximum bending moment of a comparable straight bridge.