Engineering method for estimating the reactions of transmission line conductors under downburst winds

In this study, a closed form solution to calculate the reactions of transmission line conductors subjected to downburst loads is derived. The derivation is conducted using a simplified multi-spanned conductorinsulator system, where the insulators to the right and to the left of the tower of interest are modeled using a combination of roller supports and linear springs. The considered system allows for the interaction between the spans without the need of solving a set.of non-linear equations to avoid the complexity. The closed form solution is derived to be applicable for downbursts with arbitrary size and location relative to the line. The solution is then focused on a critical downburst case that is previously recommended for the line design. Accuracy of the derived solution is assessed under both downbursts with arbitrary size and location and downbursts corresponding to the critical case. The assessment is carried out by comparing the conductor reactions obtained using the proposed solution with those from the Finite Element Analyses (FEAs). It is found that the predicted reactions by the proposed solution are in a very good agreement with those from the FEA in both the transverse and the longitudinal directions. For example, the highest differences for the critical case are found equal to 2% and 8% for the reactions in the transverse and the longitudinal directions, respectively. This indicates that the solution is reasonably accurate given the complexity of both the downburst wind field and the structure behavior of the conductor system. The proposed solution represents a practical and useful tool for practitioner engineers involved in the design of transmission lines, particularly under downburst winds. (C) 2015 Elsevier Ltd. All rights reserved.