Punching shear capacity of steel-fibre recycled aggregate concrete slab

Abstract

For this paper, the punching shear behaviour of 18 steel-fibre recycled aggregate concrete (SFRAC) balanced slab–column connections was experimentally investigated and analytically modelled for the following variables: the recycled concrete aggregate replacement level (0, 50 and 100%) and the volume fraction of hooked-end fibres (0, 0.4 and 0.8%). The measured punching shear capacities were practically insensitive to the recycled aggregate replacement levels, although both the inclination of the punching failure surface as well as punching capacities increased with fibre dosage. Relatively, the best performance improvement was obtained at 0.4% fibre dosage wherein the punching capacities and energy absorption increased by 23% and 70%, respectively, as compared to the non-fibrous concrete specimens. Using the experimental results, the authors propose and calibrate a simple strut-and-tie based punching shear predictive model for SFRAC, and undertake a validation using the limited results available in the literature. Among the selected current design codes under appraisal, the most conservative punching shear predictions for the SFRAC specimens were obtained from the Indian code, IS456:2000, whereas relatively more accurate predictions were obtained from the Eurocode 2.