Reinforced Concrete Beam Reinforced By GFRP-polymer Mortar Sheet

Fiber Reinforced Polymer(Fiber Reinforced Polymer or Fiber Reinforced Plastic(FRP))has the advantages of high tensile strength,corrosion resistance and fatigue resistance,and has been widely used in structural reinforcement in recent years.FRP reinforcement of concrete members is mainly divided into two ways:external reinforcement and in vivo reinforcement.The common point of these two ways is that the FRP material is pasted on the lower surface of concrete through the adhesive layer,so as to achieve the effect of reinforcement.Therefore,the study of mechanical properties of FRP-concrete interface is the core problem of reinforcement technology.By strengthening method for sheet sticking GFRP reinforcement and polymer mortar,GFRP rebar-polymer mortar mainly make full use of the GFRP reinforcement plate tensile strength,high modulus of elasticity,good rigidity and good viscosity polymer mortar,the advantages of fast curing,the two materials together into a thin plate on strengthening concrete beams.First,the interface bonding property of GFRP bars and polymer mortar sheet was studied through double shear test.On the basis of the test,the mechanical process of GFRP bars and polymer mortar sheet reinforced beams was simulated.The main work contents of this paper are as follows:(1)Through consulting information,we learned that the factors affecting the bond performance include concrete strength,FRP material,bond width and length,and loading method.Then according to these influencing factors,different grades of concrete test blocks and different lengths of GFRP bars-polymer mortar sheet were designed,and double shear tests were carried out to study the failure forms of bond interface.(2)under the action of static load,and analyzed the damage form of interface,discovered the different grade of concrete strength and the influence of different bond length sheet to the bearing capacity,and use in GFRP reinforcement in advance-polymer mortar on the sheet strain gauge measuring strain value under the load at all levels and different distance from the loading end of strain values,and then draw strain curve under the different load and different distance from the loading end strain curve.Through the obtained strain curve,the stress curve was indirectly deduced,and the slip value was obtained by integrating the strain curve,and then the bond slip curve was drawn.Finally,the theoretical model was verified by data.(3)Introduces the selection of the model,and builds the constitutive model for each component,and also gives a brief overview of some special Settings in the process of modeling.Based on different length(800 mm,900 mm,1000 mm,1100mm)of thin plate as a variable,respectively,different grades of concrete(C30,C40)reinforced beams are analyzed,through the simulation test of the stirrup strain curve and the curve beam stiffness of concrete beam according to the strain curve of the ultimate load and yield load are obtained the very big enhancement,the deflection is also gradually decreases,and cracking resistance of beam has been enhanced,found in the sheet length is 900 mm when the reinforcement effect is best,not the longer the length of reinforcement effect of sheet,the better,in actual reinforcement structure,To determine the most appropriate amount of GFRP-polymer mortar sheet,but also found that with the increase of concrete strength,the strengthening effect is more obvious.A relatively low strength grade of concrete,concrete crushed,the concrete is make full use of,GFRP sheet-polymer mortar nor be pulled,utilization rate is low,no reinforcement effect,with the increase of concrete strength level,GFRP sheet-polymer mortar played a reinforcement effect,by making full use of,has finally been tensile failure.(4)By comparing with the unstrengthened beams,the working principle and three stages of the failure process of the strengthened beams are summarized.According to the theory of flexural reinforcement and the basic assumption criterion of the flexural capacity of the normal section,the failure modes are divided.According to the division conditions,the ultimate bearing capacity formula of the section is deduced and verified.