Experimental Study On Bond Performance Between Near-Surface Mounted CFRP Laminate Strips And Concrete Interface With Beam Tests

Fiber reinforce polymer(FRP)has been widely used in the field of concrete structure maintenance and reinforcement for nearly 30 years due to its light weight,high strength,corrosion resistance and good fatigue resistance.At present,the common FRP bending reinforcement methods are: external reinforcement reinforcement method(EB-FRP),embedded reinforcement method(NSM-FRP)and mechanical fastening method(MF-FRP).Compared with the current research and application of the external reinforcement reinforcement method,the embedded reinforcement method can effectively avoid the interface peeling damage of the reinforcing member,and can better protect the fiber material from the external environment.However,there are few studies on FRP laminate strips reinforced concrete structures.Therefore,the embedded reinforcement method has a good application prospect and research value in the field of concrete structure maintenance and reinforcement.In this paper,the interface properties of Near-Surface-Monted CFRP laminate strips reinforcement concrete are studied.The strengths of different concrete(C40,C80),different bond lengths(100mm,150 mm,200mm)and different CFRP laminate strips are analyzed.Strip,2,and 3)The effect of the failure mode of the embedded reinforcement system,the end slip of the CFRP laminate strips,and the local stress-slip relationship.The main research contents and conclusions of this paper are as follows:(1)The influence of concrete strength,bond length,and number of CFRP laminate strips embedded on the failure mode of the embedded reinforcement system.There are two main failure modes of the test piece: interface failure and concrete corner shear damage.When the number of CFRP laminate strips is 1 and the length of the affixing is long,the main failure mode of the specimen is interface failure,while the specimen with high concrete strength(C80)is generally CFRP laminate strips-Sika30 The joint detachment failure of the joint with low concrete strength(C40)is generally the Sika30 rubber-concrete interface peeling failure.When the number of CFRP slats is large(2,3),the main failure mode of the test piece is concrete shearing damage.The longer the bond length,the larger the area where the interface peels off before the other damage occurs.(2)Influence of concrete strength,bond length,and number of CFRP laminate strips embedded on the end slip of CFRP laminate strips.The specimens with different variables have the same slope of the axial force-constrained end relative to the slip curve,while the ultimate restraint end slip value and the CFRP laminate strips ultimate axial force increase with the increase of concrete strength and bond length,embedded with CFRP laminate strips.The number increases and decreases;the CFRP laminate strips free end slip value is negligible relative to the overall slip.(3)The influence of concrete strength,bond length and CFRP laminate strips embedded quantity on the local bond-slip relationship of embedded reinforcement system.The ultimate bond stress bond strength and ultimate slip value increase with the increase of concrete strength and bond length,and decrease with the increase of the number of CFRP laminate strips.The fitting test data shows the locality of different interface failure types.Stress slip model.