Thermal cracking of concrete slabs reinforced with fibre reinforced polymer bars

Use of fibre reinforced polymer (FRP) reinforcement in concrete structures has increased remarkably in recent years.; This research presents the results of an experimental investigation into the behaviour of FRP reinforced concrete slab panels under the effects of thermal gradients. Temperature gradients were produced by heating the top surface of the specimens using infrared lamps while the bottom surface was exposed to room temperature. The specimens were simply supported at the corners while the displacement at the centre of the slab was restrained to zero to produce statically indeterminate moments causing tensile stresses at the bottom surface of the slab. The bending moment and the cracking developed by the thermal gradients were monitored and the strains in the reinforcement and the widths and spacing of the cracks were recorded. Following the thermal loading test, the specimens were subjected to a downward mechanical point load applied at the centre and increased monotonically up to failure. The results were compared to those obtained from testing a control specimen of the same dimensions but reinforced with conventional steel bars of the same reinforcement ratio 0,6 percent. The experimental investigation showed that the specimen reinforced with carbon FRP bars exhibited the best performance under thermal or mechanical loading in comparison with the specimens reinforced with steel or glass FRP bars. Smaller crack widths, strains in the reinforcement, and deflections were obtained in the carbon FRP reinforced specimen. (Abstract shortened by UMI.)...