Multiparameter Fatigue Analysis of a Steel-Super-Toughness-Concrete Lightweight Composite Bridge Deck

This study aimed to comprehensively analyze the effects of the thickness of a super toughness concrete (STC) layer, the thickness of diaphragms, and the spacing of stud shear connectors on the fatigue property of a lightweight composite bridge deck. A multi-parameter analysis was performed on a steel-STC lightweight composite deck to facilitate its fatigue design. Based on a real bridge, a serial local finite element model was built to calculate the fatigue stress range of the typical fatigue-prone cracking details of the steel bridge deck under different combinations of the three parameters. On the basis of the FE analysis, the nominal stress of each fatigue-prone detail was obtained, and the following observations were obtained. First, the lightweight composite bridge deck structure could strongly enhance the local stiffness of the steel bridge deck, but its contribution to the global stiffness of the bridge deck is limited. Second, increasing the STC layer thickness from 45 mm to 60 mm could further reduce the fatigue stress range of fatigue-prone details in the steel deck. Third, increasing the thickness of the floor beams could improve the cracking details at the U-rib-to-diaphragm connection and butt weld at the U-rib lower edge, and the stress range reduction is about 20%-29%. Fourth, reducing the spacing of the stud shear connectors could obviously decrease the stress range of the U-rib-diaphragm welded joints and the arc cutouts in floor beams, and the stress range decreases by 22.01%-27.96%.