Rational Design Spectra for Structural Reliability Assessment Using the Response Spectrum Method

Current design spectra, which approximate uniform hazard or risk spectra, are known to have shortcomings, but no alternative has been proven superior for the purposes of design checks. In this work, we use response spectrum method analysis to show that the "design point" associated with a structural reliability assessment is a rational choice for a design spectrum. When the response parameter of interest is sensitive to excitation at a particular period, the design point corresponds to a conditional mean spectrum (CMS) conditioned on that period. In the case where there are multiple structural response parameters of interest, or it is unknown what excitation periods are important to the structural response, the CMS can be used by considering multiple conditioning periods and taking the maximum structural response from any of the spectra for design checks. This observation is used to justify the CMS as a target response spectrum for design checks.