Resumen
Lightly reinforced concrete beams fail in a brittle manner, due to steel fracture soon after cracking of concrete. In order to avoid such a brittle failure andprovide certain ductility at failure, codes of practice give formulae for minimum longitudinal and transverse reinforcement. This reinforcement is meant toresist loads beyond the first crack load and ensure that failure occur after the formation of several small cracks, improving the ductility of the beams.These design criteria are based mainly on empirical studies, and different code formulae lead to quite different amounts of minimum reinforcement, particularlyfor high strength concrete beams. In this work a theoretical and experimental investigation for the determination of the minimum shear steel ratio of concretebeams with different strength, having compared the formulae of different authors and code design is presented. The experimental program included testson fourteen beams: seven of those were made of high strength concrete while the others seven had normal strength. Most of these beams had shearreinforcement in the wide range of variation of the minimum reinforcement proposed in the literature. It is also discussed which procedure would be themore appropriate for the determination of minimum shear steel ratio.