Galvanic corrosion induced localized defects and resulting strength reduction of circular steel tubes under axial compression: An experimental study

Corrosion-induced durability has become a critical issue for aging spatial structures using steel tubes as primary load-carrying structural components. Tremendous efforts have been made in predicting the ultimate strength of steel tubes under axial compression but understanding corrosion-induced buckling remains a challenge due to uncertainty of localized defects. To experimentally investigate the effect of localized corrosion on steel tubes, a modified galvanic method was developed to generate predefined corroded defects at targeted locations. A total of 24 tubes with different slenderness ratios were produced with various localized corroded defects, and then axially compressed to obtain ultimate strengths. Our experiments showed that the galvanic method could efficiently generate localized defects that could change the direction of buckling and significantly lower the ultimate strength of tubes. Further, the corrosion depth has the largest effect on the residual capacity of the tubes among three geometric characteristics of corroded patches. The influence of circumferential corrosion size is greater than that of longitudinal corrosion size due to the deviation of section centroid. From a practical perspective, our experiments indicate that the ultimate strengths of steel tubes can be lower than those estimated by both US and Chinese codes when the localized corrosion ratio exceeds 15%. Thus, the localized corrosion should be checked regularly during the maintenance routine such that buckling-induced failure can be avoided in advance.