Effects of wind attack angle and corrosion degradation on the wind resistance and failure mechanisms of transmission tower–line systems

To investigate the effects of wind attack angle and corrosion degradation on the wind resistance of transmission tower–line systems, a 110 kV double-circuit tower–line system was selected as the study case. A coupled finite element model was established using ANSYS APDL, and the fluctuating wind field was simulated using the Kaimal spectrum with Davenport spatial coherence. Dynamic responses under five wind attack angles, namely 0°, 30°, 45°, 60°, and 90°, were analyzed. Incremental dynamic analysis was employed to evaluate the ultimate wind resistance, while LS-DYNA was used to simulate progressive collapse under representative wind directions. The results show that wind attack angle significantly affects the dynamic response and failure characteristics of the tower–line system. The most pronounced dynamic response occurs under the 90° transverse-wind condition, whereas the 45° case exhibits the lowest ultimate wind speed of 42 m/s among the examined directions, with the 60° case showing a comparable value of 44 m/s. Under 90° wind loading, collapse is governed mainly by compression–bending instability and severe deformation in the mid-height region of the tower body, whereas under 45° oblique wind loading, tower-leg instability leads to global overturning. Under the 90° transverse-wind condition, corrosion degradation reduces the ultimate wind speed from 47 m/s in the uncorroded state to 41.5 m/s after 50 years of service.