Wind tunnel tests on wind loads acting on an angled steel triangular transmission tower

• Wind tunnel tests on an angled steel triangular transmission tower were carried out.
• The parameters for calculating wind loads on triangular tower bodies were determined.
• A calculation method for the effective projected areas of triangular tower bodies was proposed.

Wind tunnel tests on scaled models of a triangular transmission tower body made by angled steel members were carried out. The drag coefficients of the total tower body or single frames at nine different test cases were obtained. The experimental results from wind tunnel tests were also mutually validated by computational fluid dynamics (CFD) analysis. The parameters for calculating wind loads on triangular tower bodies determined by wind tunnel tests were compared with the calculated values by some applicable design standards. For the regular triangular tower body with an equivalent solidity ratio for three lateral faces, the experimental curves of the skewed wind load factor Kθ approximately appear like W shape and symmetrical to the axis of θ=60°. Kθ is decreased to the minimum value when the wind incidence angle is 40° or 80°. When the solidity ratio of face A is different from the other two faces, the symmetry axis of the skewed wind load factor Kθ is shifted to θ=50°. Kθ is decreased to the minimum value when the wind incidence angle is 30° or 70°. The varying trend of Kθ, especially for the wind incidence angle corresponding to the minimum Kθ value in British standard, are quite different from the experimental results. Based on a combination of the drag coefficient of single frames and the shielding effect factor, a calculation method for the effective projected areas of triangular tower bodies was proposed. Especially for the wind incidence angle θ of 0° or 120°, the calculated values of the effective projected areas agree well with the experimental values obtained from the total tower-body models.