ABSTRACT
This paper discusses the state-of-the-knowledge in the use of energy concepts in seismicresistant design of structures emphasizing issues and future directions in the use of such concepts for proper establishment of design earthquakes. After a brief review of the nature of the earthquake problem, the need for improving the earthquake-resistant design of new structures and the proper upgrading of existing hazardous facilities is discussed. Emphasis is placed on the need and the difficulties of conducting nonlinear (inelastic) seismic design. The difference between design and analysis is pointed out, and the role of nonlinear analysis in the design process is discussed. The state-of-theknowledge in the use of energy concepts in seismic-resistant design of new structures and particularly in the selection of proper (efficient) seismic upgrading of existing hazardous facilities is summarized. The importance of reliable estimation of the input energy of possible earthquake ground motions at the site of the structure in order to select the critical motion (i.e., to establish the proper design earthquake) is emphasized. The different engineering parameters that are needed for proper establishment of the design earthquake are discussed, concluding that while the input energy, Ej , is a reliable parameter for selecting the most demanding earthquake ground motion, it alone is not sufficient for proper design of the structure. For the sizing and detailing of a structure, it is necessary to specify the smoothed inelastic response spectra as well as the time history of the dissipated energy. Recommendations for research and development needs to improve the use of energy concepts in seismic-resistant construction are offered.
