Lap-Spliced Rebar Connections with UHPC Closures

Abstract

Ultrahigh performance concrete (UHPC) is gaining attention from the bridge community as a compelling option for closure pours that complete prefabricated bridge element (PBE) connections; these connections typically use field-cast UHPC cast over noncontact lap-spliced reinforcing bars to achieve structural continuity between elements. The goal of this study was to investigate the behavior of different commercially available UHPC-class materials for prefabricated bridge deck connections using noncontact lap splices. Two types of experiments were conducted to assess performance: a direct tension pullout test and a component-level prefabricated-bridge-deck connection test. The objective of the pullout testing was to investigate the effect of the UHPC fiber-volume fraction on UHPC-to-rebar bond strength and compare the performances of different UHPC specimens with existing design guidance. Component-level testing was used to investigate the bond between the UHPC and precast concrete, cracking behavior under cyclic loading, behavior during long-term cyclic loading, and monotonic ultimate-loading behavior. Findings indicated that available design guidance held for different UHPC-class materials. Furthermore, test results were used to propose additional guidance related to the UHPC fiber-volume fraction and cover requirements.