The Effect of Damping on the Seismic Response of Equipment in Buildings

Abstract

<p>This thesis studies the effects that nonproportional damping has on the vibrational characteristics of two and three level systems. In additions, error levels in response prediction are estimated for two simplified time history procedures and a response spectrum technique. It is shown that nonproportional damping creates significant changes in the damped frequency, damping ratio and mode shape of each mode of vibration of the system relative to those found for a similar system exhibiting proportional damping. The study of the prediction of the maximum system response to seismic basic motions demonstrates that there exist three regions where different dynamic analysis procedures should be used. A physically uncoupled analysis should be used for large mass ratios. A complex modal analysis should be used if the mass ratio is of an intermediate value. Diagrams are supplied which allow one to readily determine which of the three methods is the most appropriate for a design.</p>