Earthquake amplification factors for self-supporting telecommunication towers

In the absence of specific guidelines for the seismic analysis of self-supp orting telecommunication towers, designers may be tempted to apply building -code approaches to these structures. However, these towers respond to eart hquakes in a different fashion than shear buildings. In this study, earthqu ake amplification factors for the base shear and the total vertical reactio n of self-supporting latticed telecommunication towers are suggested based on modal superposition analysis performed on 10 existing towers, each being subjected to a set of strong-motion accelerograms acting in the horizontal and the vertical directions separately. Results are presented in detail fo r two of the towers studied, with heights of 66 and 121 m, respectively. Si mple regression analyses are performed on the results from which the base s hear and vertical reaction amplification factors are found. These factors a re presented as functions of the tower's largest flexural period or largest axial period of vibration as appropriate, and can be used by designers to estimate the expected level of dynamic forces developed in self-supporting telecommunication towers due to an earthquake.