Wind-Induced Vibration Behaviour of Additional Conductor and Service Safety of Fittings in Railway Overhead Contact Lines Under Canyon Winds in Harsh Environments

This study investigates the wind-induced vibration of railway overhead contact line additional conductors and the service safety of fittings in high-altitude canyon environments. Using the Dadu River canyon railway corridor as the engineering background, a three-dimensional stochastic wind field with temporal and spatial correlations is generated by combining the Kaimal, Tieleman and Panofsky spectra with a fourth-order autoregressive model. Wind-speed histories are converted into wind loads using quasi-steady aerodynamic theory. A geometrically nonlinear model based on the absolute nodal coordinate formulation is established, with suspension and support fittings represented by a swingable rod element and three-directional equivalent stiffness, respectively. Time-domain, rainflow-counting, power-spectral and parameter-sensitivity analyses are performed. Results show that fitting type strongly affects conductor-end response but has limited influence on mid-span vibration. Suspension fittings release wind-induced deformation through swinging, reducing stress peaks and high-amplitude cycles, whereas support fittings restrain end displacement but increase local constraint reactions and fatigue risk. The findings support fitting selection and wind-resistant fatigue design for additional conductors in canyon railway overhead contact lines.