Experimental and numerical assessment of the bond behaviour of laser-cut reinforcement

Reinforced concrete is a carbon-intensive technology, with concrete production contributing to 4%–8% of global CO<inf>2</inf> emissions, while steel production for reinforcement bars accounts for approximately 1.5% of global emissions. The use of concrete and steel in reinforced concrete can be minimized by optimizing the reinforcement layout and including reinforcing elements with variable cross-sections. This can be achieved through laser-cutting from steel sheet bespoke reinforcing elements that can then be assembled in optimized arrangements. However, a significant challenge in applying optimized laser-cut steel reinforcement is understanding the bond mechanisms between the reinforcement steel and the surrounding concrete to achieve composite behaviour. This study explores the bond behaviour of laser-cut reinforcement. A systematic experimental programme is designed to understand the effects of reinforcement geometry and surface treatment techniques on bond behaviour. Additionally, a numerical framework is developed to assess the mechanisms driving the transfer of bond stresses in the case of ribbed laser-cut reinforcement. The results indicate that incorporating ribs with appropriate spacing can increase the bond capacity by approximately six times in comparison to smooth laser-cut reinforcement, achieving a bond strength that falls between that of conventional smooth and ribbed rebars. The numerical results show that ribbed laser-cut reinforcement shares bond-stress transfer mechanisms with traditional ribbed rebars, with chemical adhesion and friction playing a significant role at low levels of slip, and mechanical interlocking dominating at higher slip levels. These findings have the potential to reduce material consumption through the use of optimized laser-cut steel reinforcement and provide a foundation for further optimizing the bond performance of laser-cut plates.