Interface stress analysis and fatigue design method of steel-ultra high performance concrete composite bridge deck

Orthotropic steel-UHPC composite deck consists of orthotropic steel deck and ultra-high performance concrete (UHPC) layer. The shear force transferred by shear studs at the interface between steel deck and the UHPC layer is a key in fatigue design. Based on the finite element (FE) whole model analysis of composite deck, the detailed submodels of composite deck segments with single stud and single row studs were established respectively. It aimed to investigate the interface stress distribution and slip behavior of steel-UHPC composite deck under negative bending moment, and explore the failure mechanism of short headed stud. In term of shear force relationship, considering likely influences such as location and pattern of loading, flexural stiffness of the composite deck and stud arrangement, the whole model analysis results were compared with the submodel analysis results, and a fitting formula of shear relationship between the two models was proposed. A formula for fatigue design of short headed stud in orthotropic steel-UHPC composite deck was also proposed. In respect to the longitudinal and transverse shear force distribution of studs, composite deck stiffness, hot spot stress of fatigue prone details of steel bridge deck and the maximum stress level of UHPC layer, the evaluation method of stud arrangement was proposed. The calculation results were assessed and compared with the stud layout schemes of three actual steel-UHPC composite decks, and the effectiveness of the design formula was validated.