Structural Response of Plan-Curved Steel I-Girder Bridges from an Equivalent Straight Bridge Analysis

Abstract

A set of equations was developed to estimate the maximum mechanical elements and midspan deflections of plan-curved steel I-girder bridges. These formulas were obtained from a statistical correlation analysis based on the results of 54 tridimensional finite-element models corresponding to different 3-span continuous curved bridges. The parameters that varied from one model to another were curvature radius, span length, and number of girders (i.e., load lanes). Two different live-load models were studied separately: the HL-93 and the IMT 66.5. The proposed formulas estimate the maximum mechanical elements of girders, such as positive and negative bending moments around the major and minor axes of girders, vertical shear force, torsional moment, and deflection at the midspan of girders, as a function of the results corresponding to an equivalent straight bridge. Different formulas are proposed for interior, intermediate, and exterior girders in accordance with the bridge cross section and for central and extreme girders in accordance with the span where the girder is located. For each bridge model, the maximum mechanical elements and midspan deflections were normalized with respect to the corresponding results of an equivalent straight bridge with the same characteristics of the curved bridge (span lengths and number of girders), but with a curvature radius equal to ∞. The accuracy of the proposed formulas was tested for different bridge models considered in the correlation analysis, and the results show that they are accurate enough to be used for design purposes. In some cases, they were more accurate than current applicable formulas and procedures recommended in the literature. However, special care must be taken in the applicability of these expressions because they were obtained from models with particular characteristics.