Development of a new equivalent analysis technique to determine the ultimate load in an electric transmission tower

The current design practice of an electric transmission tower is based on allowable stress design method in Korea. However, it is difficult to find reasons for the collapse of a transmission tower designed with this approach because the collapse tends to occur as a result of secondary large deformations. The main influential factors of nonlinear behavior are residual stresses, initial imperfections, and the end restraints on members. In this study, the necessity of the new analysis technique is examined through a comparison of elastic analysis and inelastic analysis. A new equivalent analytical technique (EAT) is proposed as a means of minimizing the complexity. Furthermore, the reliability of the proposed method is validated by comparing the computed ultimate load of the transmission tower with that of nonlinear finite element analysis.