STR-886: EFFECT OF CONCRETE STRENGTH ON THE PUNCHING SHEAR BEHAVIOUR OF GFRP-RC SLAB-COLUMN EDGE CONNECTIONS

This paper presents the results of an experimental program carried out to investigate the effect of concrete strength on the punching shear behaviour of concrete slab-column edge connections reinforced with glass fibre-reinforced polymer (GFRP) bars. Six full-scale connections were constructed and tested to failure under gravity loads. Three connections were made of normal strength concrete (NSC), while the other three were made of high strength concrete (HSC). The dimensions of the slabs were 2,800×1,550×200 mm with a 300-mm square column extending 1,000 mm above and below the slab. All connections were reinforced with GFRP sand-coated bars without shear reinforcement. Three flexural reinforcement ratios were employed for each concrete strength; 0.90, 1.35 and 1.80% in the direction perpendicular to the free edge. All connections failed in a brittle punching mode. The HSC connections showed less deflections and strains in both reinforcement and concrete at the same load level than their NSC counterparts. Also, doubling the concrete strength (from 40 to 80 MPa) slightly increased the capacity by 10, 3 and 5% for connections with reinforcement ratios of 0.90, 1.35 and 1.80%, respectively. Moreover, the Canadian standard for FRP-reinforced concrete buildings provided reasonable predictions with an average experimental-to-predicted ratio of 1.29±0.05 and 1.22±0.05 for the NSC and HSC connections, respectively