Fire Exposure Effects on Galvanized Steel: Field Evidence from Utility Pole and Anchor Assessments

Fire events affecting above-ground infrastructure frequently trigger conservative replacement decisions due to uncertainty in assessing residual material performance. Galvanized steel utility poles and telecommunication tower anchors are particularly susceptible to such post-event actions, as visual indicators such as discoloration, soot deposition, and coating alteration are often interpreted as evidence of structural degradation. This study demonstrates how integrated, multi-disciplinary condition assessment methods can provide objective evidence of post-fire serviceability and prevent unnecessary asset replacement.

Two field case studies are presented. The first evaluates a galvanized steel utility pole exposed to a localized vehicle fire, and the second examines telecommunication tower guy-wire anchors subjected to wildfire conditions. Comprehensive assessments were performed using electrochemical potential measurements, galvanized coating and wall-thickness evaluation, hardness testing, scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS), field metallography and replication (FMR), and soil corrosivity characterization. Despite pronounced visual fire effects, all measured parameters confirmed retention of coating protection and mechanical integrity in both systems.

The case studies are complemented by the introduction of a high-temperature remote monitoring sensor capable of measuring thermal exposure up to 2,000 °F, enabling improved correlation between fire severity and metallurgical response. Results collectively demonstrate that visual fire damage indicators alone are poor predictors of structural impairment and underscore the value of quantitative, evidence-based post-fire assessment protocols for galvanized steel infrastructure.