下击暴流作用下输电塔线风致响应及易损性研究OA

Downburst winds are characterized by high wind speed,short duration and strong spatial localization,whereas current wind-resistant design of transmission lines still insufficiently considers the wind load characteristics and tower-line coupling effects.To investigate the dynamic response and fragility characteristics of transmission tower-line systems under downburst winds,this study employs computational fluid dynamics simulation,finite element dynamic analysis and Monte Carlo simulation to establish a three-dimensional downburst wind field and a 220 kV transmission tower-line system model.By comparing the wind speed profile simulations obtained using the Reynolds stress model(RSM)and shear stress transport(SST)k-ω turbulence model,the study analyzes the response differences between the equivalent tower-line model and the three-tower four-line coupled model at different wind directions.Fragility curves are then developed by taking initial member yielding and global yielding as damage states.The results show that the RSM turbulence model can reasonably reproduce the vertical distribution of near-ground horizontal wind speed.When the wind direction is perpendicular to the conductors,the conductors and insulator strings transmit additional lateral forces and torsional effects to the tower through the cross-arms,leading to an approximately 27%increase in tower-top displacement in the three-tower four-line coupled model compared with the equivalent tower-line model.Although downburst winds can produce high local wind speed,their limited spatial extent results in relatively lower wind-induced risk for towers located outside the core wind speed region.The findings provide a reference for wind-resistant checking and fragility assessment of transmission tower-line systems in regions prone to severe convective winds.