Aerodynamic damping of telecommunication lattice towers

Lattice towers are structures generally considered to be sensitive to wind loading, mainly due to their low mass. However, low mass structures possess considerable aerodynamic damping which has a reduction effect on the along-wind induced dynamic response. The main purpose of the study is to investigate the effect of various parameters such as the force coefficient and the design velocity pressure on the aerodynamic damping of antennae towers. As such, a parametric study consisting in the design of seven towers of various heights, i.e. 90m, 80m, 70m, 60m, 50m, 40m and 30m to along-wind loading has been conducted. All towers have a triangular in-plane section. Circular cross-sections were used for leg members whereas both circular as well as angle cross-sections were used for diagonal, horizontal and secondary members. All towers have been considered to be equipped with both ancillaries as well as antennae, the same configuration being used for all the design cases. Similar values of aerodynamic damping were obtained for towers of similar heights, irrespective of the cross-section of bracing members. Also, results show that the reference velocity pressure used in design has little influence on the aerodynamic damping value