Shear Resistance of Steel-Fibre Reinforced RC Beams with Small Circular Openings

This paper reports test results from two experimental programs on RC beams with small circular openings under the combined action of bending and shear. Simple design rules are proposed and compared to the test results. The presence of openings leads to a disturbed stress flow which may result in early cracking and sudden failure if additional reinforcement is not provided close to the openings. This reinforcement is often tedious to place. Hence, it was decided to check if the reinforcement layout could be simplified by the inclusion of short discrete steel fibres in the concrete. Two experimental programs were undertaken: one with single openings and one with double openings The main test variables were the amount of steel fibres (0 or 1.0vol%) and the layout of the shear reinforcement. It was found that all shear reinforcement could be left out by the inclusion of 1.0vol% steel fibres in the concrete. This also led to a more ductile post-peak behaviour of the structural members.