Assessment of wind-induced fatigue life for transmission tower-line systems incorporating joint probability distribution of wind speed and direction

To investigate the influence of wind direction on the fatigue of transmission tower-line systems, a joint probability distribution model for wind speed and direction was established based on 40-year measured wind data from Xinjiang. Using the S–N curve method, the response patterns of the tower-line system under various wind conditions were analyzed, and the wind-induced fatigue life was evaluated based on this distribution. Results indicate that variations in wind attack angle and speed significantly affect the fatigue characteristics of sensitive components. The primary sensitive regions include the main structural members near cross-arms and the upper chord members of the lower and middle cross-arm tiers. Fatigue damage in sensitive members decreases with increasing wind attack angle, with the most severe damage occurring at a 0° wind attack angle. Fatigue damage at member ends is significantly higher than that in central regions. Even at lower wind speeds, stress amplitudes at the ends may exceed the material’s fatigue limit. The fatigue lives of top chord members on crossarms and vertical main members are 64.3 years and 66.9 years, respectively. During maintenance, reinforcement efforts should prioritize high-damage areas to ensure the safe operation of transmission lines.