ABSTRACT
Designs of buildings and structures for seismic loads are traditionally based on experience of the performance of structures in past earthquakes. Althugh the large uncertainty in the earthquqke loadings has long been recognized by engineers, it has not been fully accounted for in the code procedures other than in the selection of a design earthquake. Since the design earthquake is used in conjuntion with a series of factors to account for effects of structural period, site soil condition, inelastic, behavior, importance of the structures, etc., the reliability and safety of the final design remains unknow and undefined. The recent sentiment of the research community and design professionals is that there is a need for development of design procedures based on consideration of the physics of the problem and explicit treatment of the uncertainties. Such procedures may be used as the basis for development of next generation of buildings codes (AU)
