Thermally-induced demands due to hot dip galvanization of high mast illumination poles. Part I: Finite element model development

Abstract Hot-dip galvanizing is a protective coating process widely-used to prevent corrosion damage in steel structures. Although the protective coating greatly reduces corrosion rates, there have been many documented cases in which cracks have formed in steel members during the galvanizing process, and the root causes of those cracks remain poorly understood. This paper presents a three-dimensional finite element (FE) model capable of simulating temperature-induced deformations during galvanization of high-mast illumination poles (HMIPs), which can be used to calculate the stress and strain demands at different stages of the galvanizing process. Thermo-mechanical analyses of the FE model were performed using the commercial finite element analysis software Abaqus. A user film-subroutine was developed to simulate the transition of a pole between two different temperature environments throughout four stages of the galvanizing process, dipping, dwelling, extraction, and cooling. Numerical simulation results showed regions of the pole with the highest potential for crack initiation at critical stages of the galvanizing process. Mechanical response variables of the simulations were highest at the bends of multi-sided poles, at the welded connection between the base plate and the pole. Inspection reports show that many cracks have been detected at this location, which corroborates the validity of the FE model.