Critical Buckling Load and Nonlinear Post-Buckling Response of Guyed Towers

The lateral resistance provided by the inclined cables to pylons of cable stayed bridges and communication tower masts is approximated by means of the equivalent spring method, proposed in the literature by several researchers. At first, a simple pylon is considered supported laterally by a set of two symmetrically arranged inclined cables. The concept of substituting the cables with a spring of equivalent stiffness is employed and the critical buckling load of the pylon is calculated analytically, based on linear buckling theory. Then, the above substitution is used in order to investigate the stability of such structures by means of nonlinear finite element analyses. Namely, the analytical solution is compared to numerical results, which are generated through linearized buckling analysis (LBA) of the spring-supported pylon as well as geometrically nonlinear analysis with initial imperfections (GNIA) of the actual cable-supported pylon, employing finite element software ADINA. The unstable nature of the post-buckling response and the imperfection sensitivity of such structures are highlighted and design implications are discussed.