Energy density spectra in actively controlled inelastic structures - theory

A method of generating energy density spectra obtained front earthquake response in actively controlled structural models is proposed for practical application based on the definition of different energy forms. Both clastic and inelastic energy density spectra arc generated to study the energy transfer among various energy components. In the parametric study of clastic spectra with active control, the control force restraint parameter is adopted as an additional parameter in addition to the two commonly used parameters (i.e. natural period and damping ratio), and the yield displacement is adopted as the additional parameter in the analysis of inelastic spectra. In this first part of the research. numerical studies arc carried out for both elastic and inelastic controlled structures using optimal linear control and ad hoc control algorithms. The energy density spectra of the three main components of the input energy. i.e. damping energy, control energy. and plastic energy, of the inelastic structure are investigated using two methods: (1) by varying structural stiffness; and (2) by varying structural mass. These energy density spectra for structures with a range of periods are evaluated and compared to verify their engineering significance. Copyright (c) 2005 John Wiley & Sons, Ltd.