Design wind loads for transmission towers with cantilever cross-arms based on the inertial load method

Abstract

Appropriate design wind loads can effectively avoid damage to transmission towers under strong wind and the wind-induced vibration coefficient β(z) is a critical parameter for determining those loads. Based on the inertial load approach, a step-by-step calculation method for the design wind loads of transmission towers considering the effects of cross-arms and diaphragms was proposed. In order to be consistent with actual transmission towers, the correction coefficient expressions of β(z), such as θb, θl and θη, considering the influence of local shape, mass and windshield area and the spatial correlation of the fluctuating wind, respectively, were derived and investigated. By the introduction of these three coefficients, the design wind loads for transmission towers with cross-arms and diaphragms can be determined. For transmission towers with cantilever cross-arms, design wind load formulae were derived, based on the analyses of 6 tower samples. The example of an actual transmission tower was used to verify the correctness of the derived formulae. The parameter analyses of the design wind loads showed that cross-arms have a great influence on β(z) and the wind-induced vibration response of transmission towers, but diaphragms only have a marginal influence and so may be neglected in the approximate calculation of the design wind loads. The research results provide a calculation method for the wind-resistant design of transmission towers.