Evaluation of Minimum Flexural Reinforcement in Design of Reinforced Concrete Beams

Abstract

Reinforced concrete (RC) beams are generally designed with different percentages of flexural tension reinforcement depending on the capacity requirements. The amount of reinforcement provided affects the crack propagation and failure mechanism in RC beams. This paper presents discussion on the minimum tension reinforcement requirement in code provisions for RC beams. Models based on fracture mechanics to evaluate minimum flexural reinforcement are also reviewed. Experimental study has been undertaken to understand the effect of size on the behaviour of lightly RC beams. This paper outlines how the present code provisions can be improved by applying fracture mechanics principles for the design of RC beams. Fracture mechanics approach for design of RC structures considers the energy requirements for crack growth and size effect. It also enables rational procedure to evaluate the optimum amount of steel reinforcement, which ensures safe designs by taking the effect of size and other influencing parameters.