SEISMIC HAZARD ANALYSIS OF NONLINEAR STRUCTURES .2. APPLICATIONS

In a companion paper, a methodology for the direct computation of the annual seismic risk of postelastic damage in realistic, nonlinear, multi-degree of-freedom structures was developed. This methodology makes use of the (random) response factor F-DM to characterize the damage potential of future ground motions coupled with conventional spectral-acceleration probabilistic seismic hazard analysis. The present paper provides the detailed procedure for the empirical estimation of the (mean) nonlinear response factor E[F-DM] for real, complex structures. Seismic hazard curves of several types and multiple levels of postelastic damage for these two structures are also displayed. The two illustrations (large 3D steel-jacket offshore linearities: steel and soil material non-linearity, and softening geometric nonlinearity, both locally (buckling diagonal braces) and globally (the P-Delta effect). The application is made practical by the relatively few nonlinear dynamic analyses necessary. Improved software and computational efficiency has brought such analyses within the same general accessibility and cost range as linear dynamic analyses.