Current Design Spectra: Background and Limitations

The purpose of this paper is to present some observations about response and design spectra, and about certain selected topics pertaining to seismic design that will need to be developed in further detail if improved design procedures are to occur. The earthquake engineering literature is replete with articles on spectra and their applications in analysis, in part because of the simplicity of the approach offered by this design tool; nonetheless, as pointed out later in this paper, spectra, as currently employed, provide quite limited information. It is our belief that future advances in seismic design procedures will require a somewhat different assemblage and evaluation of input and response information than is currently the case. This paper will offer some observations on this subject on the basis of current research and practice.