Abstract
The impress current method is applied to acquire corroded steel bars embedded in concrete, and three-dimensional(3D) laser scanning techniques are applied on corroded steel bars to obtain the cross-sectional radius of corroded steel bars. Statistical analysis shows that with the increase of corrosion degree, the variation of radius of corroded steel bars increases linearly. For different types of steel bars, plain round steel bars have a larger sensitivity to corrosion than ribbed ones. Original radius of steel bars and mixture proportion of concrete have negligible effect on the variability of radius of corroded steel bars. A normal distribution model is obtained to describe radius data of corroded steel bars. For the convenience of practical application, the indicator,R, which is the ratio of the average to the minimum cross-sectional areas of corroded steel bars, is introduced to quantify the longitudinal variation of the cross-sectional areas. By using Monte-Carlo simulation, the indicator, R, of corroded steel bars are achieved based on the probability distribution of radius. The indicator R can be fitted well by the Gumbel distribution, and the distribution parameters increase linearly with the increases of corrosion degree.
Highlights
Corrosion of steel bars in concrete has become one of the predominant factors leading to performance degradation of concrete structures
It is obvious that the relationship among the mean value, the variation of radius and the average corrosion degree of corroded steel bars of a certain length can be described with an identical equation
Where ρ is the density of steel ; A0, r0 are the original nominal cross-sectional area and radius of steel barrespectively; A, r are cross-sectional area and redius of corroded steel bar, and the subscript represents the element number ; m is the number of r obtained from one cross section ; μ, σ are the mean value and standard deviation of r respectively
Summary
Corrosion of steel bars in concrete has become one of the predominant factors leading to performance degradation of concrete structures. A corroded reinforced concrete beam may fail at an uncritical section with a smaller cross-sectional area which is not subjected to the maximum moment, and the failure probability of the beam may increase. In order to investigate the impact of the longitudinal variation of cross-sectional areas on mechanical properties of steel bars and to predict failure probability of reinforced concrete members, variability of cross-sectional areas of corroded steel bars should be investigated. To calculate the load bearing capacity and failure probability of corroded RC members, the calculation of the minimum cross-sectional area is of vital importance. The cross-sectional radius of corroded steel bars are investigated in this paper instead of getting crosssectional areas because of the small sample size of areas. The stochastic process model of cross-sectional radius of corroded steel bars is established. The probability distribution and influence factors of indicator, R, are analyzed
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