Analysis of Corrosion‐Fatigue Damage and Fracture Mechanism of In‐Service Bridge Cables/Hangers

Abstract

Cables/hangers are important load-bearing components of suspension, cable-stayed, and through-arch bridges. Their reliability throughout their service life directly affects the safety of these bridges. In this study, to provide a reference for the design, maintenance, and inspection of bridge cables/hangers, their damage and failure mechanisms were theoretically analyzed using finite element analysis and corrosion-fatigue simulation tests of steel wires, based on the characteristics of the cable/hanger damage. The finite element analysis showed that a rotation of 0.00113 rad in the lower anchorage area results in a bending stress of 18.8 MPa, indicating that the effect of the bending stress on the steel wires in this area cannot be neglected, as it is a factor contributing to the failure of long cables/hangers. We further used a salt spray chamber to simulate an acid-rain environment. The results showed the following: (1) corrosion-fatigue damage of the cables/hangers occurs under the combined action of a corrosive environment and an alternating stress. This leads to an intensified corrosion damage, reduced ductility, increased brittleness, and eventually, brittle fracturing of the cables/hangers. (2) In the same corrosive environment, the highest degree of specimen corrosion occurred during alternating stress, followed by static stress, and no stress. (3) After corrosion-fatigue damage occurred for a specimen, its breaking stress was about 60% in comparison to the uncorroded specimen. The percentage elongation at the break also decreased; this was about 40% in comparison to the uncorroded specimen, indicating brittle fracturing. (4) The steel wires of the cables/hangers with corrosion-fatigue damage are more prone to brittle fracture if they are exposed to complex spatial stresses.

Fatigue Life Evaluation of Parallel Steel-Wire Cables under the Combined Actions of Corrosion and Traffic Load

“…Yao et al [13,15] concluded that the coupling of the stress state (stress amplitude and pretension), and the corrosive environment signifcantly afects the fatigue performance of high-tensile steel wires. Under the same corrosive environment, the corrosion of high-tensile steel wire under alternating and constant tensile stress conditions is more signifcant than that under no stress.…”

“…When the protective system of the stay cable is damaged, the steel wire in the cable is directly exposed to the corrosive environment, which aggravates the corrosion of the highstrength steel wire in the stay cable [10][11][12]. Te fatigue test data of corroded steel strands under diferent stress conditions in reference [13] showed that the stress state (stress range and mean stress) had a signifcant efect on the fatigue properties of the steel strands. Li et al [14] established a time-dependent depth model of uniform and pitting corrosion based on accelerated corrosion experiments.…”