RESEARCH ON IDENTIFICATION OF WIND LOAD DRAG COEFFICIENT OF TRANSMISSION TOWER STRUCTURES UPON MONITORING DATA

The transmission tower structure is an important carrier of transmission lines, which is closely related to economic construction and energy security. The drag coefficient is an important parameter for wind-resistant design of transmission tower structures. The values in the current codes refer to the results of wind tunnel test and numerical simulation, which is difficult to be measured on site. A wind load reconstruction method based on acceleration and strain is thusly proposed, and then a drag coefficient identification method is established upon the measured wind speed data, which solves the problem of accurately obtaining the drag coefficient of transmission tower structure from the perspective of field measurement. The dynamic displacement is calculated from the acceleration and strain data. The structure is simplified into a condensation model and the wind load is reconstructed. The drag coefficient is calculated by combining the wind speed data. The numerical simulation of lattice tower proves the reliability of the method proposed, and the results show that the maximum reconstruction error is only 4.1 %. During the landing of typhoon Mangkhut, the applicability of the method proposed to the actual structure was further verified by the monitoring data collected on a transmission tower. The comparison between the reconstructed drag coefficients and the code values shows that the drag coefficient decreases with the increase of wind speed, and that the measured value of the drag coefficients at high wind speed is obviously smaller than the code value.