Punching shear behaviour of shear reinforced concrete slabs

This study investigates the punching shear behaviour of reinforced concrete slabs with various shear reinforcement, including newly developed metallic fibres. Six slab specimens of dimensions 1800 3 1800 3 120 mm are constructed. The test parameters include fibre type, shear reinforcement type and fibre volume fraction. Conventional steel fibres, amorphous metallic fibres (AMFs), stirrups and stud rails are used as shear reinforcement and fibre volume fractions of 0%, 0.6% and 0.8% are added into the concrete. The test results show that the use of AMFs in concrete could improve the peak load and maximum deflection of slabs subjected to direct shear. The addition of 0.8% fibre volume fraction of AMFs into concrete increases the peak load and maximum deflection by 35.39% and 72.41%, respectively. In contrast, stirrups and stud rails used as shear reinforcement show less contribution to the increase of the peak load and maximum deflection. The test results are compared with the predictions by current design codes of the Korea Concrete Institute, KCE 2012, and the American Concrete Institute, ACI 318-11, and strength models. Based on the limited test results, a resistance model for evaluating the strength resistance of AMFs is developed, and its prediction is compared with the test results.