Optimization of stiffness and damping coefficients of connection dampers to reduce the dynamic response of transmission line steel towers subjected to wind action

Abstract

Tall and slender latticed steel towers, such as power transmission line towers, are very susceptible to vibrations imposed mainly by wind action. Thus, changing the design layout or making use of vibration control devices is often necessary to reduce vibration amplitudes and avoid the collapse of the structure. In this work, an alternative to the conventional types of commercial dampers is the use of elements in the connections of the structure, such as rubber rings working like connection dampers, so they can dissipate the energy of the system reducing the dynamic response of the tower. Thus, this work proposes a methodology for the optimization of stiffness and damping coefficients of connection dampers in structures of latticed steel towers of Transmission Lines (TL) that are subjected to the dynamic effects of wind. An illustrative example is presented. First, the structure is evaluated considering perfectly rigid connections; then the stiffness and damping coefficient of the connections are optimized in order to minimize the vibration amplitudes of the tower. Finally, the natural frequencies, damping ratios and maximum horizontal displacements are compared for situations of perfectly rigid and semi-rigid connections. The results show that the optimization process results in a structure with a fundamental frequency of vibration similar to that of the original tower, however a significant reduction in the horizontal displacements can be observed, since an increase in damping occurs, thus proving the capacity of the proposed methodology.