Punching strength of slabs reinforced for shear with offcuts of rolled steel I-section beams

Punching shear failure may occur at columns supporting flat slabs or at concentrated loads. The rupture is brittle and may occur clearly below the flexural capacity of the slab. This work aims to analyse the symmetric punching resistance of reinforced concrete flat slabs with shear reinforcement. Twelve 200 mm thick slabs representing regions around columns, loaded at the centre and reacted at the edges, were tested up to failure. Short offcuts of steel I-beams were used as shear reinforcement. The principal variables considered in the tests were the area, number and distribution of the shear steel elements. All the slabs failed by punching, and the failure load of the specimen with the most reinforcement was more than twice that of the slabs without shear reinforcement.