Seismic Response of Light Subsystems on Inelastic Structures

Preliminary analyses are performed to obtain insight into the seismic response of light, acceleration sensitive nonstructural subsystems supported on structures that yield during severe earthquake ground motions. The effects of the severity of the inelastic deformations, of different hysteretic characteristics of the structure and of the amount of viscous damping of the subsystem are thoroughly investigated. Current design recommendations for subsystems accounting for yielding of the supporting structure are assessed and found to be unconservative. An amplification factor is defined to quantify the effects of inelastic deformations of the supporting structure on subsystem response. Design guidelines are formulated for predicting the amplification factor based on statistical evaluation of the results generated for ten earthquake ground motions. Using these values, design floor response spectrums can be obtained from conventional linear elastic floor response spectrums accounting for yielding of the supporting structure without having to perform inelastic analysis.