RESEARCH ON WIND FIELD MEASUREMENT AND WIND-INDUCED VIBRATION RESPONSE OF THE SUSPENSION-BRACED TRANSMISSION STRUCTURE IN MOUNTAINOUS GORGE

The wind field in mountainous gorge is significantly affected by terrain, and its characteristics are quite complex, which has a significant impact on the wind-induced vibration response of the suspension-braced transmission structure crossing mountainous gorge. In view of this, obtaining the characteristics of the canyon wind field and thereby investigating its impact on the wind-induced vibration of the structure constitutes the essential first step in the related research. The gorge wind field where a suspension-braced transmission structure is located was investigated via a field measurement at first. Based on measured data, the mean and fluctuating wind characteristics of the wind field were analyzed, and the measured power spectrum was fitted. By incorporating the characteristics of the canyon wind field, a wind‑induced vibration analysis model for the suspension‑cable‑supported transmission structure is developed. With this numerical tool, the effects of the canyon wind field on the responses of the structure are quantitatively revealed. The results show that: The distribution of wind direction samples with lower mean wind speed is more discrete, while for samples with mean wind speed of no less than 8 m/s (i.e., strong wind samples), the wind direction is more concentrated. The correlation between wind attack angle and wind direction angle of strong wind samples is significant. The mean values of the turbulence intensities of longitudinal, lateral and vertical are 0.25, 0.20 and 0.15, respectively. The measured power spectrum has higher spectral values than the theoretical spectrum, and it appears to be higher in the high-frequency range. Compared with the wind field simulated by the theoretical spectrum, the mean and mean square deviation of midpoint lateral displacement of the conductor in the gorge wind field increase by 3.16% and 3.26%, respectively, while the mean and mean square deviation of vertical displacement increase by 7.85% and 6.62%. Under the canyon wind field, the statistics (mean and mean square deviation) of the lateral displacement response of the supporting‑conductor suspension cable are relatively close to those obtained from the wind field simulated with the standard wind spectrum, while the mean and mean square deviation of vertical displacement increase by 62.14% and 15.28%, respectively.