Shear-friction behavior of grooved construction joints between a precast UHPC girder and a cast-in-place concrete slab

Abstract

As an advanced cement-based composite material, ultra-high - performance concrete (UHPC) has been widely used in bridge engineering due to its superior mechanical properties and durability. One of the most efficient bridge structures consists of composite beams with precast UHPC girders and cast-in-place concrete slabs. There is limited knowledge, however, about the shear behaviour of UHPC-substrate construction joints. In order to address this issue, this study is carried out to examine the shear-friction behaviour of joints between precast UHPC girders and cast-in-place concrete slabs by means of push-off tests, varying slab type, shear reinforcement ratios and interface treatments. Experimental analysis indicates that reinforcements across the joints could significantly improve the ultimate shear resistance of an interface to a UHPC substrate with a groovedsurface. Additionally, the shear stress of the interface is also affected by the cast-in-place slab type. The surface treatment of the grooved surface was also found to be an efficient method for improving the shear capacity of an interface between a precast UHPC girder and a cast-in-place concrete slab. Finally, to predict the interfacial shear strength between precast UHPC girders and cast-in - place concrete slabs, a more precise equation, based on the AFGC 2013 design guideline, was proposed and validated by experimental results presented in this paper and beyond. The proposed design equation could lead to safer and more reliable design of such type of bridge joints.