Analysis Of Interface Stress Of Concrete Beam Strengthened By Bonded Steel With Quartz Sand In Adhesive Layer

The method of strengthening reinforced concrete beams with steel plates is widely used in engineering practice.Many researchers at home and abroad have carried out a large number of experiments or finite element software numerical simulation research on the structural carrying capacity and interface stress of steel plate reinforcement components,and the research results have been relatively mature.Therefore,if we want to improve the effect of steel plate bonding,we must actively develop the new technology of steel plate bonding which is different from the traditional method.At present,in view of the research results that quartz sand,as a mineral admixture,can improve the material performance to a certain extent,this paper proposes a new method of strengthening concrete beams by sticking steel plates with quartz sand in the adhesive layer.The interface debonding is always a key problem to restrict the strengthening effect of externally bonded steel plate.Therefore,this paper will study the mechanical performance,failure mode and bonding interface stress of the bonded steel members with silica sand in the adhesive layer by means of experimental analysis,numerical simulation and theoretical analysis,analyze the influence of each parameter on the mechanical performance and stress mechanism of the strengthened beams,and put forward the reasonable sand content bonded steel reinforcement method with theoretical and experimental support for engineering practice.The main contents are as follows:(1)Based on the theory of elastic mechanics,this paper analyzes the rubber with the stress of the steel reinforced concrete beam form of quartz sand,by considering respectively concrete beam,adhesive layer and mechanical equilibrium and deformation coordination of steel sheet,steel plate is deduced on the backend interface shear stress and normal stress analytic expression,and with the sub without quartz sand adhesive interface stress analytical solutions of steel reinforced concrete beam were analyzed.(2)Through the double-sided shear test of steel plate and concrete with silica sand in the adhesive layer,the influence of different quartz sand content on the interface bonding performance is studied,and the distribution law of the surface strain of steel plate and the transfer law of the interface shear stress are analyzed.(3)Based on the experimental data of double-sided shearing,the bond-slip curve at the interface of the cement-steel-reinforced concrete beam containing quartz sand in the glue layer is derived.Nakaba again based model,its critical control parameter is corrected,the finally obtained steel sheet containing the adhesive layer of quartz sand-slip model interfacial adhesion of concrete.(4)Based on the numerical simulation study,the mechanical performance,interfacial slip and reinforcement effect of externally attached steel plate strengthened beams with different quartz sand contents were analyzed.The numerical simulation results are compared with the physical test results,and the results show that the addition of the initial quartz sand can not enhance the reinforcement effect,but also lead to the decline in the adhesive performance of the rubber layer.When the proportion of quartz sand is in the range of 1/3?1/2,the reinforcement effect of adhesive steel is improved,and then the reinforcement effect of increasing the content of quartz sand begins to decrease.