Experimental Study On Impact Resistance Of FRP-confined Concrete

Fiber reinforced polymer(FRP)has the advantages of anti-corrosion,high strength,easy construction and low cost.After forming the outer FRP confined concrete structure using concrete columns,when the external axial pressure is applied to the concrete,the concrete is in the third state of compression,the ability to enhance the bearing capacity and deformation of concrete columns,such FRP reinforced concrete structures and other structures the large number of applications.As the international situation is more complex,more and more rampant terrorism,large-scale energy and a variety of factors,chemical plants inherent in some of the security risks and other makes military defense,industrial and civil buildings are likely to suffer intense during service the impact of the role of explosions,collisions and so on.With respect to the common static load,these complex dynamic loads greater damage to FRP-confined concrete structures caused.Therefore,the impact resistance of FRP-confined concrete research is necessary to provide a theoretical reference for large-scale application of FRP in the actual project.In this paper,the impact mechanical properties of FRP-confined concrete specimens are studied.The effects of FRP types(AFRP,BFRP and CFRP),number of wrapping layers(0,1,2 and 3 layers),strength of core concrete matrix(C30 and C60)and strain rate on the impact resistance of FRP-confined concrete are studied.The failure modes,dynamic stress-strain curves,dynamic compressive strength,dynamic increase factor and energy absorption varying with strain rate are obtained.The test results show that: 1)the compressive strength of FRP-confined concrete and unconfined concrete increases significantly under impact load,and with the increase of strain rate,the dynamic compressive strength of FRP-confined concrete and unconstrained concrete increases gradually,and both FRP-confined concrete and plain concrete have strain rate effect;2)under similar strain rate,the same concrete matrix strength,the same FRP material,with the increase of strain rate.The dynamic compressive strength of FRP-confined concrete specimens increases with the increase of the number of wrapping layers(0,1,2 and 3 layers);3)Under similar strain rates,the dynamic increase coefficient of FRP-confined high-strength concrete specimens is less than that of FRP-confined ordinary strength concrete specimens with the same number of wrapping layers;4)Under similar strain rates,the same number of wrapping layers,the same strength of concrete matrix,and AFRP-confined high-strength concrete specimens.The dynamic increase coefficient of concrete specimens is larger than that of BFRP-confined high-strength concrete specimens,and the dynamic increase coefficient of BFRP-confined high-strength concrete specimens is larger than that of CFRP-confined high-strength concrete specimens;5)Under similar strain rates,the absorbed energy of AFRP-confined high-strength concrete specimens is larger than that of CFRP-confined high-strength concrete specimens with the same matrix strength and the same number of wrapping layers.The absorbed energy of the specimens is larger than that of the specimens confined by BFRP;6)By statistical analysis of the experimental data and related research data,the dynamic compressive strength model of FRP confined concrete under different strain rates is obtained by linear regression analysis.