Nonlinear elastic and inelastic spectra with inherent and supplemental damping

SUMMARY During severe seismic events, structures designed according to current standards yield and develop inelastic deformations. While the acceleration responses are limited by the yielding strength, these structures develop permanent deformations (and possible damage) due to such yielding. Spectra developed for inelastic structures can help in determining the desired yield levels and the associated inelastic deformations. Some structures made of special materials or equipped with innovative structural systems may yield, but can recover the deformation upon unloading and, thus, may avoid permanent deformations. These structures are known as nonlinear elastic. Often the post yielding excursions are very large and may exceed their toughness (or deformability). By introducing damping in form of supplemental devices, it is possible to control such deformations and keep them within acceptable limits. Spectra for such nonlinear elastic structures and inelastic structures are developed herein, by considering both inherent and supplemental damping. The difference between the two types of damping is addressed both theoretically and numerically. Design examples of several simple structures using the newly developed spectra are presented, which illustrate the importance of lower strength and damping in these nonlinear elastic or inelastic systems. Copyright © 2013 John Wiley & Sons, Ltd.