| When flowing through a hill, wind will be influenced by complex hilly terrain, and a complex hilly terrain wind field will be formed, which differs from the wind field on flat ground and will made the wind resistance design of transmission towers differ from the case on flat ground. Most of the present provisions on hilly terrain wind field of domestic and overseas codes are simple and differ from each other. Therefore further research on the the characteristics of wind field on hilly terrain has a great significance on the site selection and the wind resistance design of transmission towers.Wind tunnel test and CFD simulation are engaged to investigate the characteristics of wind field on typical hilly terrain. Hill models of different slope are made in a scale ratio of1:500in wind tunnel test. Tests of single hill and double hills are carried out. The influence of slope on wind field of single hill, and that of slope, spacing of hills and wind direction on wind field of double hills are investigated. Results on typical locations are compared with provision of domestic and overseas codes. In CFD simulation, the slopes of hill and wind direction are extended, and the influence of roughness of ground and scale of hill on the wind filed is investigated. To take full advantage of the data integrity of CFD, the characteristic of3-dimension distribution of wind field is investigated, and the flow around the hill is preliminarily analyzed. The Vector Form Intrinsic Finite Element method is engaged to calculate the wind-induced response of a transmission tower, and a new approach of the simulation of wind-induced collapse of transmission towers is discussed. Finally, the response of a transmission tower under typical hilly terrain wind field is calculated and compared with that of the case of flat ground and domestic and overseas codes.Results of the wind tunnel test and the CFD simulation indicate that there is a great speed-up effect at the top and lateral slope of the hill on account of the flow around effect. Wind speed is very low behind the hill on account of the wake zone. Results by the wind tunnel test are compared with provision of domestic and overseas codes, which indicates that results of this research are between provision of domestic and overseas codes. The response of a transmission tower under typical hilly terrain wind field is significantly larger than the case of flat ground, which indicates that the great influence of speed-up effect of hilly terrain on transmission towers should be paid enough attention in the wind resistance design of transmission towers. |
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