Evaluation of the Performance of UHPC- and HCSC-Filled Noncontact Lap Splice Closure Joint Used for Lateral Slide-in Bridge Construction

Abstract

With slide-in bridge construction, the bridge superstructure is constructed off the final alignment and then slid laterally from the temporary worksite onto the in-place substructure. Once the sliding is completed, a closure joint between the bridge super- and substructure is cast to establish continuity. The cementitious materials and reinforcement design used to complete the closure joints determine when the bridge can be opened to traffic and construction loads. The goal of this paper is to investigate the performance of closure joints filled by ultrahigh-performance concrete (UHPC) and hybrid composite synthetic concrete (HCSC) connected by noncontact lap-spliced rebar, with a specific focus on determining when a noncontact lap splice has sufficient strength to either open a bridge or to expose it to additional construction loading. To achieve this objective, a series of laboratory tests were performed on 96 samples, including four noncontact lap-splice connection designs with different rebar development lengths and joint filling materials. A time-dependent pullout test was performed during the first 28 days to capture the time-dependent ultimate capacity of each design. Further, analytical simulations were conducted to evaluate the joint performance. Finite-element models were created based on the tested samples and calibrated against the lab test data. Finally, a parametric study was performed on the calibrated models to investigate the effects of design parameters on the ultimate capacity. Based on the test results, it was found that when the UHPC reached Day 1.5, all UHPC connection designs reached the bar yield strength before failure. However, HCSC samples showed better performance regarding the ultimate pullout capacity than the UHPC samples during the earliest stages of material cure (before 1.5 days). Moreover, the parametric study results showed that increasing the bar size and side cover will increase the capacity.