Mechanistic Understanding of the Non-Uniform Corrosion of Steel Bridges: From the Perspective of Micro-Environments

The prevention of non-uniform corrosion in steel bridges remains a global challenge. Addressing this gap, the present study investigates atmospheric corrosion in steel bridges and introduces a non-uniform corrosion rate prediction process based on micro-environments, including the temperature and relative humidity of the air near the steel bridge surface (TS and RHS) and the deposition of pollutants on the steel bridge (DP). Using a CFST arch bridge as a case study, this research examines the causes of non-uniform corrosion and explores effective protective measures. The findings reveal a maximum of 1.48 °C for the TS and 15.7% for the RHs in different parts of the arch ribs. Significant disparities of the DP are observed in different parts of the arch ribs. The largest DP at the upper chord is up to 44.3 mg/m2/day (mdd), and the smallest amount of deposition at the lower chord is close to 0 mdd. Under the influence of the aforementioned factors, significant non-uniform corrosion of the ribs was found, with the fastest corrosion rate being up to 18.5 μm/year and the slowest corrosion rate being close to 0 μm/year. Uneven pollutant deposition is the primary cause of the non-uniform corrosion of the CFST arch bridge. By conducting the regular cleaning of the ribs, non-uniform corrosion could be mitigated.

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