Approximating Frequencies of Tall Buildings.

A Rayleigh quotient is developed to calculate estimates of the fundamental frequencies of tall slender buildings. The quotient provides simple analytical frequency estimates that agree well with results reported using a more detailed beam model and finite-element analyses. It is also shown that the fundamental frequency varies inversely with the height of the building being modeled, and that the additional stiffening provided by one model of an outrigger appears not to appreciably alter the fundamental frequency. [ABSTRACT FROM AUTHOR]