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This paper presents a systematic evaluation approach that allows the design professional to estimate the performance of damaged buildings subjected to sets of ground motions representing different hazard levels. The performance of damaged buildings for a future seismic event prior to repair and/or rehabilitation was evaluated using an elastic model and stiffness of the structure. The linear static model using the damaged state of brittle fractured connections in steel moment resisting frame buildings provides a reasonable estimation of the interstory drift of the damaged buildings when compared to nonlinear time history analysis. Then, this result was incorporated in a reliability-based procedure that provides a degree of confidence that a building before and after the damage will exceed the given performance levels. Finally, examples of confidence level calculations are presented. The results showed that the linear static model and the performance evaluation procedure are very useful and allow the design professional to determine the level of safety of damaged buildings. [ABSTRACT FROM AUTHOR]

The performance assessment and optimal design of fluid viscous dampers through life-cycle cost criteria is discussed in this paper. A probabilistic, simulation-based framework is described for estimating the life-cycle cost and a stochastic search approach is developed to support an efficient optimization under different design scenarios (corresponding to different seismicity characteristics). Earthquake losses are estimated using an assembly-based vulnerability approach utilizing the nonlinear dynamic response of the structure whereas a point source stochastic ground motion model, extended here to address near-fault pulse effects, is adopted to describe the seismic hazard. Stochastic simulation is utilized for estimation of all the necessary probabilistic quantities, and for reducing the computational burden a surrogate modeling methodology is integrated within the framework. Two simplified design approaches are also examined, the first considering the optimization of the stationary response, utilizing statistical linearization to address nonlinear damper characteristics, and the second adopting an equivalent lateral force procedure that defines a targeted damping ratio for the structure. These designs are compared against the optimal life-cycle cost one, whereas a compatible comparison is facilitated by establishing an appropriate connection between the seismic input required for the simplified designs and the probabilistic earthquake hazard model. As an illustrative example, the retrofitting of a three-story reinforced concrete office building with nonlinear dampers is considered. [ABSTRACT FROM AUTHOR]