###### Abstract  
The purpose of this paper was to investigate the influence of long-term corrosion on the deterioration of wind resistance of a steel transmission tower during its service life. An analytical model for predicting the long-term corrosion depth of carbon steel was established, and the corrosion depth of carbon steel in the Ningbo area was predicted based on the local atmospheric environment data. With the help of typhoon full-track simulation and wind field simulation technology, a joint probability distribution model of multidirectional extreme wind speeds was constructed using the t-Copula function to determine the typhoon climate of the transmission tower site. Finite element models of the ZM4 cathead transmission tower under 30/60/90 corrosion years were then established, respectively, according to the predicted corrosion depth of carbon steel in Ningbo. Three damage modes, i.e., minor damage, moderate damage and severe damage, corresponding to the transmission tower under wind loads, were defined, and pushover analyses were used to determine the limit values of each damage mode so as to obtain the typhoon-induced fragility curves of the transmission tower within 30/60/90 corrosion years. The results show that the increase in corrosion age leads to a deterioration in the nominal mechanical properties of the transmission tower components, making the damage probability to the transmission tower increase. Under the typhoon wind loads of a 50-year return period in the most unfavorable wind direction in Ningbo, the probability of moderate damage of the tower is within 10% and the probability of minor damage is controlled between 10% and 40%. t 2022  
current national standard, \"Corrosivity Classification of Atmospheric Environment\" [1], the atmospheric environment is mainly divided into an urban atmosphere, rural atmosphere, marine atmosphere and industrial atmosphere. Among them, the marine atmosphere and industrial atmosphere are typical corrosive atmospheric environments. In the marine atmosphere (the corrosion mechanism is shown in Figure 1), the high concentration of chloride ions is the main factor causing the corrosion of carbon steel, dissolved in the liquid film of chloride ions and greatly enhancing the conductivity of the liquid film solution, thus intensifying the polarization reaction and making the corrosion rate increase [2]. In the industrial atmosphere (the corrosion mechanism is shown in Figure 2), sulfur dioxide and other corrosive gases are the main factors causing the corrosion of carbon steel; these acidic gases dissolved in the liquid film makes the pH value of the solution lower, thereby increasing the corrosion of carbon steel [3]. There are more and more large-span transmission projects with high towers and complex structures along China's eastern coast, which are inconvenient for detecting corrosion during the service life and cause difficulties in repair and replacement. Steel corrosion not only reduces the cross-sectional area of steel members but also decreases the remaining mechanical properties of steel. Therefore, the accurate prediction of the carbon steel corrosion depth becomes an important prerequisite for the performance assessment of corroded transmission towers in service. Starting from the 1950s, countries such as the United States, the United Kingdom, the Soviet Union and Japan have successively started tests on the natural exposure of metals and nonmetals to the atmosphere. Up to now, more than 400 atmospheric corrosion test stations have been established all over the world. Based on a large number of atmospheric exposure data, various types of atmospheric corrosion maps, relevant standards for atmospheric exposure tests and evaluation methods, have been introduced [4, 5], and these results have greatly promoted the development of anticorrosion materials and protection technologies and enabled researchers to have a new understanding of atmospheric corrosion mechanisms and laws.