Variability in cross-sectional areas and tensile properties of corroded prestressing wires

摘要

This paper presents a quantitative investigation on the longitudinal variability in the cross-sectional areas of corroded seven-wire prestressing tendons. A normal distributed indicator k, which is the ratio between the average cross-sectional area loss of the central wire and that of the corresponding tendon, is introduced to quantify the differences in the average corrosion degree among wires. A Gumbel distributed indicator R, which is the ratio between the average and minimum cross-sectional area of corroded prestressing wires, is used to characterize the longitudinal variability of cross-sectional areas. With the increased average corrosion degree, the distribution parameters of k almost keep unchanged, while those of R linearly increase. Probability distributions of the two indicators were verified and modeled. Thereafter, random generation of cross-sectional areas of prestressing wires with a certain corrosion degree was achieved by the Monte-Carlo method. Numerical tensile tests were carried out on corroded prestressing wires to study the variabilities in their mechanical properties, and the results had a good agreement with experimental results. As the average corrosion degree increases, the mean value of the nominal elasticity modulus almost remains unchanged, while that of the nominal elastic limit, ultimate stress, and length of the hardening branch decreases. The coefficient of variation (COV) for each of these mechanical parameters increases with the increase of the average corrosion degree. The deterioration of tensile properties of corroded prestressing wires leads to a reduction in the reliability of prestressed concrete structures. Thus, a stochastic stress-strain relationship for corroded prestressing wires was established for time-dependent reliability analysis of prestressed concrete structures subjected to corrosion. (C) 2019 Elsevier Ltd. All rights reserved.