| Corrosion of reinforced steel will degrade the performance of reinforced concrete structures.Compared with the uncorroded steel bar,the apparent characteristics of corroded steel bar are obviously non-uniform,which makes the mechanical properties of the steel bar deteriorate in different degrees.On the basis of the original research results,the random variable Rλ,which can reflect the uneven corrosion of steel bars,is defined as the research object by using HRB335 steel bars and the characterization index data of corroded steel bars obtained from 3D laser scanning and solid model building.Then it classifies the influencing factors,determines the probability distribution of the influence of each factor on Rλ by mathematical statistical analysis,establishes the probability distribution function of Rλ under the influence of different factors,and studies the variation rule of parameters in the probability distribution function with the average corrosion rate.On the basis of Rλ,the numerical tensile model of corroded steel bar is established through mechanical tensile test of corroded steel bar,and the functional relationship between mechanical indexes of corroded steel bar and Rλ is established through numerical tensile model.By using probability theory and mathematical statistics,the random variable Rλ’s probability distribution function and its relationship with various nominal mechanical indexes are further deduced to obtain the random model of mechanical property degradation of steel bar based on the corrosion inhomogeneity.The results show that the non-uniform corrosion coefficient Rλ of corroded steel bar obeies the Gumbel distribution,and the corrosion environment,steel bar diameter,average corrosion rate and section length of corroded steel bar all affect it.The comparison of the corrosion environment shows that there is no significant difference between the mixing salt dry and wet circulation environmen and the natural corrosion.The results of parameter estimation under different influencing factors and the probability distribution model of corrosion unevenness of steel bars with different diameters show that the natural corrosion environment has the least unevenness under the same corrosion degree.The environmental inhomogeneity of salt-mixing dry-wet cycle is the largest at low current.There is little difference between full immersion environment and semi immersion environment.They are between natural corrosion environment and low current salt mixed dry wet cycle environment.The smaller the diameter of steel bar and the longer the section length,the greater the unevenness after corrosion.Through the probability distribution model of various mechanical property degradation parameters of reinforcement,it is reflected that with the increase of non-uniform,the nominal elastic modulus,nominal yield strength,nominal ultimate strength and nominal ultimate strain of reinforcement degrade,but the degradation degree of the nominal elastic modulus is very small and can be basically ignored,and the degradation of other mechanical properties is obvious. |
