Assessing the compressive strength of corroded tubular members

Abstract

The relationship between compressive strength and loss of wall thickness due to corrosion is analyzed, including consideration of Euler global buckling, inelastic global buckling, and the onset of yielding in a member with asymmetric corrosion. A limiting condition is analyzed in which external corrosion is very asymmetric and distributed in such a way as to maximize the bending moment due to eccentricity. It is demonstrated that the American Petroleum Institute design formulas for inelastic buckling are sufficiently conservative to predict the strength even for this asymmetric member. Thus, it appears that one can predict the ultimate capacity of a typical tubular bracing member without explicit consideration of patterns of corrosion. This allows thickness testing on a member within an older structure to be used in determining a conservative (i.e. lower bound) estimate of the remaining wall thickness of the member, rather than in finding patterns of corrosion.