Effect of Steel Reinforcement Type and Diameter on the Strength of Non-Contact Lap Splice Connections using UHPC

: Accelerated bridge construction (ABC) reduces construction time and lane closures. As such, these projects are effective for construction and rehabilitation of bridges in areas of high traffic or limited access. Ultra-high performance concrete (UHPC) has increased the ability of designers and contractors to effectively and efficiently complete ABC projects. UHPC provides many advantages for ABC connections due to its high compressive and tensile strength, durability characteristics, and rheological properties. In recent years, the Federal Highway Administration has been conducting research on non-contact lap splice connections for prefabricated bridge elements using UHPC. The research presented in this paper focuses on one aspect of that research: bond between steel rebar and UHPC. The overarching goal of this research was to develop design guidance for UHPC-rebar lap splices. Experimental testing was conducted to quantify the influence of concrete cover, bar type, bar yield strength, and bar diameter on the UHPC-rebar bond strength. Sixty-seven direct tension pull-out tests were conducted to supplement data from previous research. Newly conducted pull-out tests focused on larger bar diameters, and included #8 (No. 25) and #11 (No. 36) bars. The results showed that larger diameter bars and epoxy coated bars have lower capacities than uncoated bars, smaller diameter bars.