DESIGN PROCEDURES FOR SHOCK ISOLATION SYSTEMS OF UNDERGROUND PROTECTIVE STRUCTURES. VOLUME 3. RESPONSE SPECTRA OF SINGLE-DEGREE-OF-FREEDOM ELASTIC AND INELASTIC SYSTEMS

Abstract

Abstract : A discussion is presented of response spectra for single-degree-of- freedom systems subjected to different forms of ground excitation. In the study of elastic systems, the sensitivity of the response to variations in the detailed characteristics of the input motion is discussed. For each class of forcing function, simple approximate rules are presented for the construction of response spectra for undamped systems. Simple rules are described for the construction of spectra for complex input functions by compounding the spectra for the 'dominant' component pulses of the input function. In the studies of inelastic systems, primary attention is given to elastoplastic systems and, in an exploratory way, to bilinear systems of the softening type. Response spectra are presented from which the yield resistance required to limit the maximum deformation of the system to a prescribed multiple of its limiting elastic deformation can be determined directly. The maximum deformation of an inelastic system is related to that of an elastic system having the same initial slope in its resistance-deformation diagram and, for certain conditions, simple design rules are formulated for the construction of deformation spectra for elastoplastic systems in terms of the corresponding spectra for the associated elastic systems.