Punching shear capacity of GFRP bar-reinforced concrete slabs-on-ground

This work investigated the punching shear capacity of slabs-on-ground reinforced with GFRP bars subjected to concentrated loads. A total of 12 slabs measuring 1.5 × 1.5 × 0.15 m3 were fabricated with a single-layer of reinforcement grid and placed on a 100 mm-thick extruded polystyrene foam with a modulus of subgrade reaction of 124 MPa/m, simulating dense sand subgrade conditions. The variables of the study were the rebar type (two types of GFRP bars and conventional steel), spacing of bars (200 mm and 300 mm), reinforcement grid location in the slab (top-third, middle-depth, and bottom-third), location of concentrated load (center, edge, and corner), and type of loading (monotonic and repeated). The study found that the load-carrying capacities of GFRP bar-reinforced slabs were approximately 79.0 % and 91.0 % of the steel-reinforced slabs at 200 mm and 300 mm spacings, respectively. Crack patterns, failure modes, load–deflection response, punching shear capacities, deflection profiles, and strains in GFRP bars in the slabs are presented. An empirical equation is proposed to predict the punching shear capacity of GFRP bar-reinforced slabs-on-ground. The proposed equation was validated with the experimental results and the limited data reported in the literature for slabs-on-ground. GFRP bars in slabs-on-ground are a potential and sustainable alternative to conventional steel as reinforcements.