Shear design of concrete beams reinforced with grid reinforcement

A new method for designing orthogonal steel grids as shear reinforcement in concrete members is proposed, considering sectional stress distribution and failure criteria of concrete. The concept and formulations of this method have been applied to the analysis and design of reinforced concrete beams subjected to combined shear and bending. An accurate formula for calculation of shear reinforcement ratio is deduced, leading to innovative results. Shear strength of reinforced concrete beams is assumed as the sum of contributions from orthogonal grid reinforcements in the cracked zone and from concrete in the shear compression zone. Eleven reinforced concrete beams with grid reinforcement were tested under bending and shear to validate the accuracy of the proposed method. It was found that the proposed model predicts the experimental behaviour accurately and that grid reinforcement can enhance the shear behaviour of concrete beams.