Mechanical Properties Of HFRP And Bonding Between HFRP And Casting-In-Place Concrete

Fiber reinforced polymer or plastic(FRP) has been widely used in strengthening existing concrete structures as substitutional materials of steel. But strengthening the concrete structures with solefiber reinforced plastic exists some limitations such as lower capacity or ductility, and FRP/concrete composite structures represent the future of composites for construction. FRP directly substituted the steel bar in the concrete structure, the key question is bonding properties between HFRP and concrete. Aim at above-mentioned, the test of HFRP and bonding between HFRP and casting-in-place concrete are studied, in this paper. Main studied projects are as following:Based on the 70 group of FRP sheet material pulling test, the effects to the ultimate strength, modulus of elasticity and ultimate strain of GFRPn CFRP are studied. Results show that the ultimate strength, modulus of elasticity of FRP is out of correlation with layers of FRP and with the rising of layers number of FRP ,the ultimate strain of GFRP,CFRP rise too.To study the effect to different CFRP/GFRP combination ratio to HFRP destruction characteristic, longitudinal strength, elasticity coefficient as well as ductility influence, 50 group of HFRP sheet material pulling test have been carried out. Results show that GFRP volume rate about 0.8, the ultimate strength, modulus of elasticity of HFRP is non-evidence, ultimate strain is better, we can achieve the better comprehensibility of HFRP by adjusting volume rate of GFRP. Based on the analysis, the calculation formula of ultimate strength and modulus of elasticity are advanced.The effects of serious factors on the failure mechanism of wet-bonging and the bonding properties have been analyzed by 60 group of wet-bonding mechanical property test. Results show that bonding fail are all peeling in concrete, the concrete intensity and bonding capacity, the shearing strength have the certain relevance, joining the PPF and rising the stiffness of HFRP are possible obviously to enhance the bonding capacity, the shearing strength and the effective bond length. Based on the analysis, the method of calculation of effective bonding length is advanced.