Bolted steel plates for rigidly connecting decks to beams in precast concrete flooring systems

Abstract

Given the pivotal role of connections in the advancement of the precast building industry, issues such as low adaptability, construction difficulties, chain collapse, and low robustness are critical considerations, demanding the design and study of new types of connections that meet the standards and can be practically used in the industry. The current study proposes and examines, experimentally and numerically, a connection method for rigidly combining two precast decks positioned on top of a beam. Two steel plates are positioned at the top middle of the two precast floors and the underside of the beam, with highly post-tensioned bolts, ensuring a rigid connection between all elements. This research includes 12 parametric experimental and corresponding numerical studies to analyze the performance of the connections under shear and bending, with parameters including floor height, bolt dimensions, and beam width. The initial calculation approach for the connection is described and compared to empirical findings. Various failure modes, including bending, shear, and rupture of the post-tensioning bolts, may occur depending on the selected geometric parameters. The proposed connections demonstrate a high capacity for carrying up to 84 % of the load borne by monolithic elements. • High load transfer efficiency: The B P F C system effectively transferred significant shear and bending forces between connected floors and beams, closely approximating the performance of monolithic concrete elements. • Robust failure mechanisms: The study identified and analyzed failure modes such as shear, bending, and bolt rupture. This detachable connection demonstrated controlled failure behavior, avoiding sudden or brittle collapse, a critical safety feature. • Optimized bolt performance: Post-tensioning forces and bolt dimensions were shown to be crucial for achieving the complete B P F C mechanism. However, the results indicated that after a certain threshold of post-tensioning, additional force has a limited impact on further improving the connection’s performance. • Force and geometry-based controls: The developed calculation approach highlighted how key parameters, such as bolt positioning, bolt loads, and beam dimensions, influence the overall capacity of B P F C . Adjustments to these parameters can optimize the system’s performance. • Enhanced rebar configurations: The study emphasized the role of stirrups and longitudinal rebars in improving the system’s shear resistance. The B P F C can achieve performance levels equivalent to monolithic elements with proper rebar configuration. • Robotic manufacturing potential: The integration of robotic shotcrete technology and automated post-processing methods demonstrated the feasibility of a scalable, efficient production process suitable for large-scale, automated precast floor assemblies.