The Statistic Analysis On Surface Feature And Research On Degradation Model Of Mechanical Properties Of Corroded Reinforcing Bars

Steel corrosion is one of the main reasons for the deterioration of the durability ofconcrete structures. Due to the non-uniformity of the weight of the concrete, theinstability of service environment, the various parts of the reinforced by the differentforces and other factors, after the reinforcement corrosion, its surface features andmechanical properties demonstrate significant random, as a consequence, it is greatsignificance that study the distribution of surface features of the corrodedreinforcement and stochastic models of degradation of the mechanical properties toassess durability of reinforced concrete structure and make a service life prediction.As the common-atmosphere environment, the object of study is corrosion stirrupstaken from reinforced concrete structure. Analyzing the inhomogeneity of corrodedreinforced surface profile, the maximum cross-sectional loss rate and the randomnessof rust pit influencing on the mechanical properties of corrosion stirrups, establish thestochastic model for degradation of the reinforced mechanical properties.The main contents are as follows:Based on fractal theory to do a quantitative analysis of the non-uniformity ofthe corroded reinforced surface contour, the research is to get characteristics ofcorroded reinforced profile parameters. After regression analysis, the relationamong characteristics of corroded reinforced profile parameters, its mass loss rateand mechanical properties is build.Use probabilistic method to analyses the distribution of depth and width, theratio of depth and width, the maximum corrosion pit depth of corrosionreinforcing steel, the result indicates that the parameters mentioned above areobeying lognormal distribution, normal distribution and extreme value type II distribution, and then the relation between the rust pit size probability statisticalparameters and corroded reinforced mass loss rate is built.Operated corroded reinforced tensile test, the result showed the main factorsfor the degradation of the mechanical properties of corroded reinforced. The studyis selecting the maximum cross-sectional loss rate and the maximum corrosion pitdepth as indicators to build the stochastic model for degradation of the mechanicalproperties of corroded reinforced, it’s as foundation of evaluation of durability ofreinforced concrete structures.