An Experimental Investigation on the Degradation of Material Properties of Naturally Corroded Bailey Truss

In its duration of service, Bailey truss is commonly exposed to corrosion threats due to the failure of anti-corrosion coatings, resulting in corrosion damage to its steel members and degradation of its structural performance. There is a lack of research on the degradation of the material properties of Bailey truss due to natural corrosion. This paper investigated the degradation of a Bailey truss that had been in service for eight years, in northeast China. Tensile tests were carried out on corroded specimens from three truss members (the chords, diagonals, and verticals), to establish regression equations for the minimum residual cross-sectional rate and several material properties of four parts (chord flange, chord web, diagonal web, and vertical web). The equations were compared with the degradation of steel properties with different yield strengths, cross-sectional shapes, and corrosion types. Fitting formulas for the true constitutive models of the four parts of non-corroded and corroded specimens were developed. It was found that the diagonal truss member was the most severely affected by corrosion, while the chord web was the least impacted. The degradation trend of 80% in regard to natural corrosion specimens is lower than that of the Bailey truss diagonal web and the degradation trend in terms of the yield strength and ultimate strength in the same part is less than 5%. According to the Ramberg–Osgood model, the multi-curve constitutive model fitting formulas are suitable for four parts of naturally corroded Bailey truss.