Experimental study on shear performance of perfobond steel plate in ultra-high performance concrete (UHPC)-normal concrete (NC) connection

Ultra-high performance concrete (UHPC) is an innovative material owing to its merits of high strength, ductility, durability, and chloride corrosion resistance. Considering that the UHPC is expensive, UHPC is usually adopted as the composite material combined with normal concrete (NC). However, good shear bond should be ensured between UHPC and NC. To improve the interfacial performance, a novel perfobond connector was proposed and to be embedded at UHPC-NC interface. A total of 20 push-out specimens with four varying parameters were tested and two failure modes were observed in the specimens, namely cracking and separation. The mechanical properties of peak load and initial stiffness were summarized and analyzed. Analytical studies showed that the shear capacity is primarily provided by the bond (approximately 75 %). Although the dowel had little influence on shear resistance, it can substantially increase the initial stiffness up to 795 % compared to the specimens without hole in the steel plate. Finally, a unified equation for predicting shear capacity of concrete dowel and interfacial bond were derived, which agreed well with the experimental results.