Moment and Shear Distribution Factors for the Design of Simply Supported Skewed Composite Steel I-Girder Bridges Due to Dead Loading

Abstract

The sequence of loading during construction of simply supported skewed bridges influences the magnitude of stresses developed in the girders and is usually not explicitly addressed in design codes. Many designers and contractors use ad hoc methods to analyze the structural behavior during different construction phases of skewed bridges. Although bridge design permits unshored and shored construction, design guidelines to estimate the accumulation of skew girder stresses due to different load conditions (1) before the concrete hardening, and (2) after placing the asphalt layer and the barrier wall are as yet unavailable. In this paper, a three-dimensional finite element modeling was conducted to determine the moment and shear distribution factors of simply supported skewed composite I-girders under dead load conditions by considering different parameters, including skew angles, girder stiffness, cross-bracing layout, span length, and number of design lanes. Finally, the results signify the importance of considering the effect of moment and shear magnification factors for rational prediction of girder dead load stresses and support reactions, and to develop more realistic design guidelines for shored and unshored sequences of construction.