Research Of CFRP Reinforced Concrete Box Girder Bending Shear And Composite Stress

In recent years, accompanied by a substantial increase in the amount of traffic volume,the overload problem of the bridge structure is also becoming increasingly serious,and the natural environment, material aging and influence factors such as force majeure,bridge structure have produced affect a large number of the normal function of the disease, and in the bridge structure, most of them are in complex stress state, the compound force of bridge structure reinforcement increasingly subject to people’s attention.Domestic and foreign scholars about the compound stress of reinforced concrete box girder of experiment and theory study has achieved fruitful results, but for the reinforcement of box girder, stress mechanism is more complicated in complex stress conditions, still lack of thorough research.CFRP as a new kind of reinforced material, in numerous reinforcement engineering due to its advantage and the favour of people, therefore, the bearing capacity of CFRP reinforced box girder in composite under the force of experiment and theory research,is of great significance.This article has carried on the experimental study about the bearing capacity of CFRP reinforced concrete box girder under composite stress.The design and construction of the five pieces of reinforced concrete experiment box girder, and then to one of the four slices of box girder according to different ways of strengthening reinforcement, and through the test device for each box girder was graded loading test, then get the box girder is obtained under various load and deflection of each test section,strain of steel, strain of CFRP and strain of concrete,and observe the development of surface crack of loading process,after loading to record the location of beam body surface crack.The test results show that the different ways of CFRP reinforcement, the improvement of box girder torsion bearing capacity and the cracking mechanism of Box girder under bending shear and composite stress is different.Based on experimental research, the application of variable Angle space truss theory,puts forward the type torsional shear destruction of CFRP reinforced composite box girders under the stress of calculation model, and according to the equilibrium condition to establish equation, deduced the CFRP reinforcement box girder torsion limit bearing capacity formula of composite load, and compares the theoretical calculation value and experimental value.In the current design code of concrete structure by related calculation formula on the basis of the capacity of the box section are proposed strengthening the bearing capacity of torsion member correction formula.Using the ANSYS finite element software, established the finite element model of the CFRP reinforced concrete box girder bending shear stress,and the box girder specimens under load at all levels of the stress distribution are numerically simulated, calculated the box girderstiffness, steel strain curve,concrete strain curve and CFRP strain curve was consistent with the test result.