Resonant frequency and maximum rotation angle of a rocking radar tower

摘要

The effects of material damping, shear modulus, Poisson’ s ratio, excitation frequency, andrndynamic soil mass on the resonant frequency and the maximum rotation angle of motion for rockingrnvibration of a radar tower have been thoroughly investigated by using an Excel spreadsheet. Materialrndamping ratio is an important factor which should be added to the geometrical damping ratio in the vibrationrnanalyses for rocking vibration. The resonant frequency increases with the increase in shear modulus, andrnPoisson’s ratio, but the maximum rotation angle of foundation increases with the decrease in shear modulusrnand Poisson’s ratio. Geometrical damping ratios obtained based on the currently available constant values ofrnstiffness and geometrical damping are always constant and much greater than the material damping ratios. Thernnew recently developments of expressions of the dynamic stiffness, damping and the dynamic soil massrnshould be used to analyze foundation conditions of radar towers for the rocking vibration.