Wind Tunnel Test for Wind Loads of Transmission Tower Leg in Skew Wind

Abstract:

Wind tunnel tests with a high frequency force balance （HFFB） for the steel tubular and angle-steel tower leg models of two typical ultra-high voltage direct-current （UHVDC） transmission towers were completed at different wind velocities. The characteristics of the aerodynamic coefficients， the skewed wind load factors， and the wind load distribution factors were studied and compared with the calculation values from different standards. The nonlinear function of the skewed wind load factor and the angle α considering the transversal lift force were constructed and the fitting parameters were also determined via the fitting analysis of the experimental values， respectively. The results show that the drag coefficient， the resultant coefficient， and the skewed wind load factor are all M-shaped distribution in skew wind. The aerodynamic coefficients of the angle-steel tower leg model are always larger than those of the steel tubular tower leg model， while the skewed wind load factors of both are generally close. Compared with the calculation values from different codes， the skewed wind load factors are underestimated at almost yaw angles. In the calculation of the wind load distribution factors in the angle-steel tower leg， the skewed wind load factor should be triangulated by using the angle α rather than the yaw angle θ. The fitting formulas proposed in this paper can be used to provide references for engineering designs.

Key words:transmission tower;wind load;wind tunnel test;tower leg;skewed wind load factor;wind load distribution factor