Fatigue behavior of orthotropic composite bridge decks without cutout at rib-to-floorbeam intersection

Abstract

The composite bridge panel consisting of an orthotropic steel deck with no extended cutout at the rib-to-floorbeam (RF) intersection and an ultra-high performance concrete (UHPC) rigid layer was proposed, which can simplify the manufacture process and enhance economic benefit. Refined finite element models were established to analyze the stress response of fatigue-prone details, and the approach of variable thickness rib was proposed to achieve an infinite fatigue life. The effect of critical geometric parameters on fatigue performance of RF joint was further investigated, and the parameter combinations with infinite fatigue life were determined. The results show that the rib-to-deck (RD) joint indicates infinite fatigue life, and the stiffness of panel meets the requirements of specification. There is a significant stress raiser at RF joint, and Dong's structural stress reveals that the surface stress at rib side is dominated by bending stress. The effects of the thicknesses of UHPC layer and deck plate on the stress are not significant. Increasing the thickness of the rib belly as well as decreasing the floorbeam thickness and spacing can reduce the stress range of rib side at RF joint, and the 10 mm thick floorbeam is preferable. The UHPC layer can be 50 mm if the rib with variable thickness is utilized, while the UHPC is required to be 60 mm and the floorbeam spacing is 2.5 m if the rib with uniform thickness is adopted.