LAUSR

Abstract Steel-concrete composite slabs are often used as bridge decks and floors in buildings. This study examines the mechanics of composite slabs that are composed of steel plates and UHPC. Full-scale experiments of three steel-UHPC composite slabs and one steel–concrete composite slab are carried out to investigate how the number and type of shear connectors can affect mechanical behavior. Experimental results showed steel-UHPC composite slabs experienced flexural failure while steel–concrete composite slab experienced punching failure. Experimental data also demonstrated that steel-UHPC composite slabs possess superior ductility, capacity and stiffness. Among the composite slabs, the specimen with sufficient perfobond rib shear connectors (i.e. PBL shear connectors) exhibited the best flexural performance. Subsequently, the experimental results are used to develop a method to predict the bending capacity for composite slabs while taking the tensile contribution of the UHPC and the location of the cross-sectional neutral axis into consideration. The method is applicable to the specimens in this study as well as other specimens described in literature. The proposed formulas for calculating the flexural stiffness of composite slabs can accurately reproduce the load–deflection behavior for specimens under service loads. Results from this paper can guide engineers in the practical application of steel-UHPC composite slabs.