Geometric Nonlinear Analysis of Self-Supporting Structures for Overhead Transmission Lines.

This research evaluates the geometric non-linear behavior of structures often used in transmission lines (TLs) and verifies the influence of different wire lengths, average wind speeds, and unevenness between adjacent towers, using the IEC 60826 standard. Different finite element numerical models were developed considering the isolated tower and also the complete system (tower, wires, and insulator chains). The analyses revealed that a simplified model can be employed for cases of adjacent, equal-length spans, but for cases with different lengths, the effect of geometric nonlinearities (GNLs) can become expressive and influence the type of analysis to be performed. Furthermore, it was found that increasing the average wind speed may imply an increase in the longitudinal unbalance. Finally, it was concluded that the unevenness between spans should be considered when calculating the loads to be applied to the structure, even if the simplified model is used. Based on the outcomes and considering wind speeds between 30 and 40 m/s and adjacent tower unevenness between 0 and 10%, this work establishes practical design criteria to be used by designers in the design of suspension structures of TLs located in the State of Minas Gerais, Brazil. The methodology presented in this paper can be extrapolated to other regions of the country, paying attention to the fact that the recommendations proposed here are valid only for self-supporting towers. [ABSTRACT FROM AUTHOR]