Study On Bond Property Of Fly Ash Concrete And Corroded Steel Bar

The bond performance between steel bar and concrete is the important premise of reinforcement and concrete cooperative work,is also an important problem of the basic theory system of the concrete.Aiming at the problem in the bonding performance between corroded reinforced concrete with fly ash test and finite element analysis to do some research work, the main research contents include:(1) For the stability of the fly ash concrete compressive strength value, according to different ages of fly ash concrete strength test, found that age of fly ash, as the maintenance cycle is longer, the compressive strength of fly ash increased, at the same time, when the excess replace method in concrete mixed with fly ash, dosage of a certain amount of fly ash concrete compressive strength slightly more than normal concrete.(2) Through the study of the center of the steel bar in concrete block drawing test, studied the different rate of reinforcement corrosion on the bond performance between steel bar and reinforced concrete, the influence of found with rust steel, the ultimate bond strength between steel and concrete, the free end of the initial sliding of bond stress and limit load corresponding to the average slip were increases a certain degree, at the time of initial gradually decreases with increase rate of reinforcement corrosion, and with the destruction of concrete specimen, the residual stress between steel bar and reinforced concrete. At the same time, according to the test results, sliding average value, the ultimate bond strengths and the relationship between corrosion rate model.(3) In the same way, by drawing experiment respectively considering the dosage of fly ash, the strength of concrete, the effect of stirrups on bond performance between steel bar and reinforced concrete, the influence of the research shows that: other things equal, a certain dosage of fly ash in the drawing specimens of cohesive force at free end began to slip the relatively large, at the same bond stress free end slip is small, and damage is relatively cohesive force is large, it shows that a certain dosage of fly ash makes the ultimate bond strength between steel and concrete, plastic good at the same time, but with the increase of dosage of fly ash, corresponding to the ultimate bond strength decreases; Concrete of high strength corresponds to the ultimate bond strength between steel and concrete, the corresponding free end slip and small; Add the hooping effect of specimen, the ultimate bond stress between steel bar and reinforced concrete, small amount of slip and shows the effect of stirrup specimen has good ductility.(4) By combining experimental study and theoretical analysis, based on the bond-slip constitutive relation curve, typical bond-slip curve can be divided into initial slip length, splitting, the steep fall in paragraphs, damage and residual, the corresponding eigenvalue and the corresponding phase. Establishes the corresponding eigenvalue test model, and to deduce the bond-slip constitutive relation model of steel bar and reinforced concrete.(5) By ABAQUS simulation of the specimen under three different reinforcement corrosion extent of steel and concrete under various load drawing stress, strain, found that the situation of force and deformation of steel bar and reinforced concrete are in conformity with the actual;At the same time reference nonlinear spring element to simulate the bond-slip relationship between steel bar and reinforced concrete, the test results and finite element calculation results obtained by the comparison, the results of both close, illustrates the test results more accurate.(6) On the basis of experiment, establishing degradation and corrosion rate of corroded reinforcement ultimate bond stress relation model, with reinforced concrete Yang section bearing capacity calculation model for the premise, based on the concrete beam section stress strain assumption, deduce the calculation formula of the bearing capacity of corroded reinforced concrete Yang section by comparing with the existing test results, verify the bearing capacity of corroded reinforced concrete point section in this article expression has higher accuracy...