Flexural performance of precast beam‐beam connections with shear key and composites

The present study focused on novel wet precast beam‐beam connections with simplified mechanisms. The experimental program examines the influence of various factors such as rebar coupler length and placement, type of cast‐in‐situ mix, shear key, and interface coating between the precast element and new concrete. Three types of connection configurations are tested under three‐point bending loading to evaluate their structural behavior. The experimental results are discussed in terms of load‐deflection behavior, crack patterns, stiffness degradation, strength degradation, damage index, and energy dissipation, etc. Failure patterns revealed that a 120‐mm coupler in Type I specimens experienced rebar slip from the sleeve, while increasing the length of couplers to 160 mm facilitated rebar yielding. The inappropriate spacing between the coupler and element interface (termed as play area) shifted the failure towards the interface due to the inherent stiffness of the coupler. The absence of the shear key induced premature interface failure, with a notable 38% reduction in load carrying capacity compared to the control specimen. In contrast, the synergetic action of the longer coupler, wet cast‐in‐situ mix, shear key, and interface coating in Type II and Type III connections resembled the overall performance comparable to the monolithic specimen. The bond coat between old and fresh concrete along with the shear key is effective in delaying the interface cracking.