ABSTRACT
The role played by the amount of steel in the failure mode transition of longitudinally reinforced beams is studied experimentally. The span, cross-sectional dimensions and the mix properties of the test beams remained unaltered. It is found that the beam with a low amount of reinforcement (just one unanchored bar of diameter 12 mm) failed in the flexural mode, whereas by doubling the amount of reinforcement the failure mode changed to one of diagonal shear. The transition in the failure modes is explained from the viewpoint of fracture mechanics using several existing models. The merits and shortcomings of each fracture mechanics model are pointed out and suggestions put forward for their improvement in the light of the experimental evidence.
