Behavior and Fatigue Performance of Details in an Orthotropic Steel Bridge with UHPC-Deck Plate Composite System under In-Service Traffic Flows

Using field monitoring and finite-element analysis (FEA), this paper presents the results of an investigation on stress behavior and fatigue life estimation of fatigue-prone details on an orthotropic steel deck (OSD) with the ultrahigh-performance concrete (UHPC)-deck plate composite system. The work was performed on the Fochen West Bridge in southern China, a three-span-continuous OSD girder structure with a UHPC-deck plate composite system. The results of the study showed that welded details connected to the deck plate experienced one stress cycle for each passing individual axle, while other details away from the deck plate experienced one stress cycle for each passing axle group. Due to the significant contribution of the UHPC-deck plate composite system to deck stiffness, welded details connected to the deck plate experienced low stress ranges under direct wheel loads. However, local load effects under concentrated wheel loading still existed, and the magnitudes of stresses at fatigue-prone details were sensitive to the transverse position of individual wheel loads. Comparisons between FEA and field measurements indicated that the AASHTO fatigue truck may have underestimated stress ranges for fatigue evaluation of this bridge. The study concluded that all fatigue-susceptible details investigated on the Fochen West Bridge had sufficient resistance against fatigue cracking under the current traffic flows per AASHTO fatigue provisions. Finally, suggested guidance for the design of OSD with the UHPC-deck plate composite system was provided. (C) 2017 American Society of Civil Engineers.