Effect of concrete overlay cracking on fatigue deterioration of orthotropic steel bridge deck

To reasonably assess how the concrete overlay cracking affects the fatigue deterioration of the orthotropic steel bridge deck, the fatigue tests on a full-scale model were conducted. The fatigue stresses of the typical vulnerable details of the steel bridge deck after the overlay cracking were comprehensively simulated using numerical simulation, and the effects of concrete cracking on fatigue deterioration of typical details were quantitatively analyzed by applying the amplification factor of the fatigue stress to assessing the effect of crack size on the fatigue stress of each detail. The results show that, the typical fatigue stress increases of the orthotropic steel bridge deck details are very small when the crack depth of concrete does not exceed 20% of the concrete overlay thickness. The fatigue stresses of the diaphragm-U rib-top plate and the diaphragm-U rib details under the concrete overlayer are sensitive to the changes of crack length and depth, while concrete crack affects slightly the diaphragm cutout and the cambered part of U rib. The impact of the longitudinal crack is more significant than that of the transverse crack, and multiple cracks significantly increase the stress levels at the fatigue details, accelerating the fatigue deterioration of the composite bridge deck. Hence, reinforcement mesh shall be deployed to hinder crack propagation in concrete. © 2024 Chinese Society of Civil Engineering. All rights reserved.