Fatigue behavior of rib-to-floorbeam welded connections in UHPC reinforced OSDs subjected to longitudinal flexural

Abstract

In recent years, ultra-high-performance concrete (UHPC) has been extensively used in orthotropic steel decks (OSDs) to improve their structural characteristics and extend their fatigue lives. In the present study, an experimental investigation was conducted on three full-scale rib-to-floorbeam welded connections to study the influence of utilizing UHPC overlay on fatigue behavior of such welded connection in OSDs. Two rear axle loads of HL-93 fatigue truck codified in the AASHTO specification were applied in the tests and the effect of longitudinal flexural were considered. Fatigue tests were conducted with full fatigue performance including the failure modes, crack initiation and propagation paths, fatigue lives, and vertical rigidity degradations fully reported. The obtained fatigue test results demonstrated that the application of UHPC overlay remarkably extended the fatigue life of the studied rib-to-floorbeam connections; the fatigue lives at the test end (Nf) were extended by 74.6% under the effect of the same hot spot stress range. The vertical rigidity of the two UHPC reinforced specimens were degraded by 12.3% and 7.3% compared to 15.1% for the unreinforced specimen, indicating that the UHPC reinforced specimens still have considerable load-carrying capacities until the fatigue failure. Moreover, it is demonstrated that the FAT100 fatigue curve provided in IIW fatigue design recommendations could be employed to predict the fatigue resistance of rib-to-floorbeam welded joints in OSDs.