AERODYNAMIC DAMPING PROPERTIES OF TRANSMISSION TOWER ESTIMATED BY COMBINING SEVERAL IDENTIFICATION METHODS

We estimated the damping ratio of a tower-and-conductor system by combining several identification methods and full-scale measurement data which contain many components of close frequencies of the system vibrating under strong winds. Our procedure was able to extract the component of every vibration mode of the tower from a time history of the measurement data and estimated more accurate damping ratios individually. Moreover we discussed the effects of the progressive deformation of a transmission-conductor-plane due to an increase in wind speed on the development of the aerodynamic damping of tower-and-conductor system using a three-dimensional nonlinear analysis.