Cold rolling versus rotating friction welding techniques in mechanical splices: Study of the inelastic cyclic behavior of reinforced concrete columns

Abstract Selecting an optimal bar splicing technique is a pivotal challenge in reinforced concrete (RC) columns, particularly in seismic zones, due to its profound influence on structural performance, construction efficiency, and economic viability. This study presents a comprehensive experimental and analytical investigation into the inelastic cyclic behavior of RC columns incorporating threaded splices fabricated through two advanced techniques: cold rolling and rotary friction welding. The research aims to elucidate the effects of these splicing methods on critical seismic performance parameters, including displacement and curvature ductility, plastic hinge length, and energy dissipation. Experimental tests conducted on 1/3‐scale RC columns revealed that rotary friction welding splices with threaded couplers (RFWTC) significantly enhanced displacement ductility, curvature ductility, and energy dissipation capacities compared to oversize‐threaded couplers (OTC) and non‐spliced specimens. The superior performance of RFWTC splices was attributed to delayed bar buckling, improved bond strength, and extended plastic hinge zones. Additionally, an idealized backbone model for nonlinear analysis was developed and validated, demonstrating strong agreement with experimental observations. A refined equation for calculating plastic hinge length is also proposed, incorporating the influence of mechanical splices and confinement effects. The findings underscore the reliability and effectiveness of OTC and RFWTC splicing techniques for use in plastic hinge regions of RC columns subjected to seismic loading. These methods not only enhance ductility and energy dissipation but also address challenges associated with bar buckling and stress concentration, making them suitable for high‐performance structural applications in seismic regions.