Computation Method for Fatigue Strain in a Long-span Steel Bridge Asphalt Pavement by Using the Three-hierarchy Structure

Abstract

To derive the strain formulas of fatigue design for a steel bridge asphalt pavement, the three-hierarchy structure, which includes simplified models of plane bending strain for a full bridge, transverse flexural-tensile strain attributed to steel box beam torsion, and continuous laminated beam bending strain of the asphalt pavement of a partial bridge, was analyzed. Based on the model for a multi-span, elastic-supported continuous beam, the elastic foundation beam model and the main calculation parameters, namely, the equivalent support stiffness of the bracing cable, bending stiffness of the main beam, torsion stiffness of the steel box beam section, the equivalent support stiffness of bridge deck stiffener, the worst load locations for full bridge, as well as eccentric and partial loads, were analyzed. The method for calculating the flexural-tensile strain at steel deck surface was obtained by using the three-hierarchy structure model. According to the bridge deck stiffener model, the transverse flexural-tensile strain at the pavement surface exceeded 80%. On the other hand, the plane bending model of the main girder found that the strain is no more than 15% with full bridge loading. The main girder torsion model determined that the strain exceeded 15%.