Fatigue behavior of orthotropic steel bridge stiffened with ultra-high performance concrete layer

As a novel cement based material, the ultra-high performance concrete (UHPC) has been recently used in reinforcing steel bridge decks. In this paper, an orthotropic steel bridge (OSB) stiffened with UHPC layer is modeled via the finite element submodel technique. The stress responses of fatigue-prone details under wheel loads are obtained, and the fatigue performance is also evaluated. The stress tendencies observed by the finite element models are compared to the stress response data from field measurements. It is observed that an application of 45 mm thick UHPC layer on the OSB deck can reduce the stress range at deck side of rib-to-deck (RD) joint by up to 70.9%, achieving an infinite fatigue life. However, the stress ranges for the other three details are still significant, including the stress range at rib side of RD joint (with both membrane and bending stresses), the stress range on rib wall at weld end of rib-to-floorbeam (RF) joint (with both rotational and Poisson's effects), and the stress range at floorbeam side of RF joint (due to the in-plane deformation and out-of-plane twist). To reduce such significant stress ranges in achieving infinite fatigue life of the bridge under high traffic volume, the critical influencing parameters on the stress ranges are studied and selected for fatigue design. (C) 2019 Elsevier Ltd. All rights reserved.