A new approach to the design of RC structures based on concrete mix characteristic length

A new approach to the design of reinforced concrete (RC) structures is proposed. It does not rely on the traditional characteristic compressive strength of the concrete mix which is the basis of all current codes for the design of RC structures. Instead, the approach is based on the characteristic length of the concrete mix that has its origins in the concepts of fracture mechanics. Based on the research done in Cardiff University over the past 6 years on long and short beams and slender columns, it is shown that this new approach leads to a substantial reduction in the amount of reinforcing steel needed in RC structures made from high strength concrete mixes without jeopardising their ductility. This provides conclusive evidence that the current design code provisions for reinforcement based on the mix characteristic compressive strength grossly overestimate the requirements for high strength mixes leading to wastage of steel, reinforcement congestion and high cost of construction. The adoption of this new design approach, which is based on sound physical principles, should help promote the use of high performance, durable and sustainable concrete in the construction industry without increasing the cost of construction or compromising the safety of structures.