Study On The Bond Mechanical Behavior Between Sprayed Frp And Concrete Substrates

Sprayed FRP reinforcement technology is a new type of structural strengthening technology,which uses special equipment to mix the chopped fiber and resin,and spray the resulting mixture on the surface of the strengthened member.The technology has the advantages of fast construction speed and isotropic material,and is particularly suitable for reinforcing structural members with irregular surface shape and complex forces,such as beam-column joints.The interfacial bonding mechanical properties of sprayed FRP and concrete is an important factor that affects the reinforcement effect,and it is also an important index to study the common working mechanism between sprayed FRP and concrete.It is a key scientific problem to be solved urgently for sprayed FRP reinforcement technology.Therefore,it is necessary to carry out research on the bond mechanical properties of sprayed FRP-concrete interface and its influencing factors.In this paper,the interfacial mechanical properties of sprayed FRP-concrete were studied by experiments,numerical simulations and theoretical analysis.The main contents and conclusions are as follows.1.Ten specimens were tested with orthogonal method.The interface shear bearing capacity,load-slip curve,sprayed FRP strain,interfacial shear stress and bond-slip relationship of each specimen were analyzed.The effect of fiber volume ratio,sprayed FRP thickness,bond length,concrete strength and the thickness of bottom resin on the bond mechanical properties were discussed.The results show that the fiber volume fraction and the sprayed FRP thickness have great influence on the mechanical properties of interfacial bond.The strength of concrete has no effect on the mechanical properties of interfacial bond.There is a maximum effective bond length at the bond interface between sprayed FRP and concrete.When the thickness of the underlying resin increases from 0.2 mm to 0.5 mm,the interfacial bonding performance is significantly improved.2.The finite element model of sprayed FRP-concrete was established by introducing the interface unit to study the interface bonding mechanical properties.Change the parameters such as fiber volume ratio,spayed FRP thickness,bonding length,concrete strength and resin thickness of bottom layer.Compare finite element results with the experimental results.The rationality of the finite element model is verified and supplementary data and conclusions are provided for the theoretical analysis.3.Using exponential analysis model,the bond slip model and the calculation models of the interface shear bearing capacity,the maximum interfacial shear stress,interfacial fracture energy and the maximum effective bond length are deduced.Then,the calculation parameters of models are quantified.Finally,the theoretical calculation results are compared with the test results to verify the effectiveness of the analysis model.