Application of the Subset Simulation Method in Predicting the Seismic Response of an Existing Reinforced-Concrete Frame Structure

Abstract

A seismic risk assessment of a structure may be significantly affected by the representation of ground motion uncertainty. A direct probabilistic representation of the ground motion time history can be constructed based on a stochastic model that depends on the magnitude and distance of the seismic event. The uncertainties in magnitude and distance can be accounted for by using a joint probability distribution that is constructed using a probabilistic seismic hazard analysis based on the potential of the surrounding faults to produce earthquakes. An advanced stochastic simulation scheme known as Subset Simulation can then be used to efficiently compute the small failure probabilities corresponding to structural response quantities of interest exceeding specified threshold levels. Alternatively, the ground motion uncertainty can be represented by adopting a parameter known as an intensity measure and using attenuation relationships in order to relate this intensity measure to magnitude and distance of seismic events. The uncertainty in the response of an existing reinforced-concrete frame structure is obtained by following these two alternative approaches. This structure is known to have suffered shear failure in its columns during the 1994 Northridge earthquake in Los Angeles, California.