Punching shear behaviour of concrete slabs reinforced with CFRP grids

Punching shear action has been a focus for research in the field of civil engineering and using a fiber-reinforced polymer (FRP) grid is a novel configuration of the engineering materials. We present the test results of an experimental program on the punching shear performance of carbon-fiber-reinforced polymer (CFRP) grid reinforced concrete slabs. Six full-scale 1600 x 1600 x 150 mm slab specimens including one control steel reinforced concrete (RC) slab and five CFRP reinforced concrete slabs were fabricated and tested under monotonic loading till failure. The experiment aimed to investigate the effects of CFRP grids as flexural reinforcement and shear reinforcement on the punching behaviour of concrete slabs. Furthermore, three different shear reinforcement layouts were devised to verify which arrangement is better. Compared with the control RC specimen, the concrete slab with CFRP grids as flexural reinforcement reached almost the same punching strength with a lower reinforcement ratio. Moreover, adding extra shear CFRP grids was beneficial for improving the resistance of the concrete slab to punching. Among the three topological schemes of shear CFRP gird arrangements, the perpendicular layout was proven to be more effective than radial and rectangular arrangements.