Deterministic and Probabilistic Predictions of Yield Strength and Inelastic Displacement Spectra

Abstract

This paper presents deterministic and probabilistic predictions of inelastic response spectra based on a comprehensive ground motion prediction equation (GMPE). Our analysis reveals that over a wide structural period range, the magnitude scaling for an inelastic system is higher than that for an elastic system, especially for ductility levels greater than 2 and magnitude greater than 6.5. Both deterministic and probabilistic hazard analyses show that the “equal displacement rule,” to estimate inelastic displacement, is valid for small to moderate magnitudes and/or for low ductility levels. However, it underestimates inelastic deformation even for long period structures if the earthquake magnitude is large and the structure needs to sustain a large ductility. Our study shows that an inelastic GMPE can easily be implemented as part of standard probabilistic seismic hazard analysis (PSHA) packages to directly generate probabilistic hazard for inelastic response, avoiding possible over- or under-conservatism in approximating inelastic deformation from an elastic system.