According to the distribution characteristics of shear stiffnesses, masses and damps of seismiclly base isolated regular buildings along height, the simplified formulas of mode damping ratio are improved. Besides, formulas of natural frequencies, modes and earthquake response of regular buildings are summarized. The Numerical comparison between proposed mode damping ratios and the corresponding ones given by Kelly is carried out. And the results of comparison indicate that the proposed approximate... According to the distribution characteristics of shear stiffnesses, masses and damps of seismiclly base isolated regular buildings along height, the simplified formulas of mode damping ratio are improved. Besides, formulas of natural frequencies, modes and earthquake response of regular buildings are summarized. The Numerical comparison between proposed mode damping ratios and the corresponding ones given by Kelly is carried out. And the results of comparison indicate that the proposed approximate formulas of mode damping ratio in this paper are more accurate, though the expression of the approximate formulas is as simple as the Kelley's. As a result, the proposed simplified formulas can be easily applied in design of the seismically base isolated regular buildings . |