Improvements of steel-CA-UHPC composite wet joints in bridge deck system on resistance to negative bending moments: Static and fatigue tests

Abstract

This paper aims to promote the application of coarse aggregate ultra-high-performance concrete (CA-UHPC) wet joints for precast CA-UHPC bridge decks, advancing lightweight and long-durability bridges using accelerated bridge construction (ABC) technology. To enhance the crack resistance at the precast slab-wet joint interface, a steel-CA-UHPC composite wet joint including an attached steel plate at the end of the precast slab connected with the post-casting CA-UHPC by studs, was proposed. Eight static and one fatigue specimens were tested under negative moments on the effects of steel reinforcement lap-splice lengths and curing methods on failure modes, crack patterns, and load-displacement relationships. The improvements of attached steel plates in flexural strength, stiffness, crack resistance, and anti-fatigue behavior were discussed. The test results showed that the contact lap-splice length of steel bars of 10 d (d is the bar diameter) could provide comparable behavior to the welded reinforcements. The proposed wet joint increased the cracking and peak loads by 32.67% and 8.48%, respectively than those without steel plates. After 2 million cycles the maximum crack width was 0.13 mm and the residual strength was still maintained by 90%. These findings demonstrated that the precast CA-UHPC bridge decks with the composite wet joints had excellent service performance.