Analysis of Long-Term in-Service Degradation of the Shukhov Tower Elements

Abstract

The condition of old and repair steels of the Shukhov tower elements that were in service for~110 and 70 years, respectively, was analyzed. They were assessed with several mechanical characteristics: hardness, static and impact strength, and plasticity. Both steels are shown to exhibit extra low hardness and brittle fracture resistance, which cannot be explained only by the quality of rolled metal of that time, with lower mechanical characteristics of old steel. It was assumed that in-service degradation of steel properties took place due to the evolution of scattered damage. Larger elongation of old steel at lower hardness and impact strength also points to this fact. It was also found that strength and plasticity of both steels, determined in the medium of synthetic acid rain, were lower than in air. The presence of in-service damages in the bulk of the metal was confirmed fractographically, in the case of possible hydrogen absorption by the specimens from the medium, they initiate brittle fracture in the central part of their cross-section.

Features of the microstructural and mechanical degradation of long term operated mild steel

“…It is well known that the degradation of the mechanical characteristics of long-time exploited metal and formation of internal damages in it reduce the strength of the elements of such significant structures. In particular, it is important for such old metal structures, like the bridges of the late eighteenth century and beginning of the nineteenth century (Granat et al, 2010;Lesiuk and Szata, 2011;De Jesus et al, 2010 and hyperboloid lattice structures in the late nineteenth century and beginning of the twentieth century (Nykyforchyn et al, 2014(Nykyforchyn et al, , 2015Krechkovs'ka et al, 2015). Structures such as bridges, towers, etc.…”