Corrosion-Induced Stress Concentration Characteristics Study of Steel Strands in Bridge Cables Under Tension-Bending Coupling Loads

TL;DR

This study examines how corrosion affects stress concentration in steel bridge cables under tension and bending, revealing how pit geometry influences structural integrity.

Contribution

A refined numerical methodology to model corrosion-induced stress concentration in steel strands under tension-bending coupling loads.

Findings

Mass loss rate of steel strands increases nonlinearly with corrosion duration.

Stress concentration factor decreases with pit length but increases with pit width and depth.

Corrosion pit depth follows a Gaussian distribution across all corrosion levels.

Abstract

Steel strand cables, particularly in their anchorage zones, are simultaneously exposed to corrosive environments and subjected to tensile-bending coupling loads. Field observations of bridge cable failures indicate that they are primarily governed by the stress concentration characteristics of internally corroded steel strands under this complex stress state. Consequently, it is critical to investigate the corrosion-induced stress concentration characteristics of steel strands in bridge cables under realistic tension and bending coupling loads. An accelerated salt spray corrosion test was designed and conducted on steel strands in bridge cables. The mass loss rates of steel strands were analyzed to quantify varying degrees of corrosion. The morphological characteristics of corrosion pits on steel strands at different corrosion levels were observed and analyzed using a three-dimensional laser scanner. Based on the scanned data, the probability density functions for pit depth were fitted for each corrosion condition. Subsequently, a refined numerical methodology was developed to model corroded steel strands under tension-bending coupling loads. This methodology was utilized to perform a parametric study investigating the stress concentration characteristics at corrosion pits with different spatial dimensions of steel strands. The research results indicate that the mass loss rate of the steel strands increases nonlinearly with increasing corrosion duration. The depth of corrosion pits on the steel strands follows a Gaussian distribution across all investigated corrosion levels. The stress concentration factor of the corroded steel strands exhibits a significant linear correlation with the corrosion pit geometry. Specifically, the stress concentration factor decreases linearly with increasing corrosion pit length, but increases linearly with both corrosion pit width and depth. Quantitatively, a 0.1 mm increase in corrosion pit length, width, and depth results in decreases in the stress concentration factor by 0.062, increases by 0.036, and increases by 0.062, respectively.

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