Probabilistically robust nonlinear design of control systems for base-isolated structures

Abstract

A stochastic-simulation-based nonlinear controller design for base-isolation systems is discussed in this study. The performance objective is the maximization of structural reliability, quantified as the probability, based on the available information, that the structural response trajectory will not exceed acceptable thresholds. A simulation-based approach is implemented for evaluation of the performance of the controlled system. This approach explicitly takes into account nonlinear characteristics of the structural response and the control law in the design process. A realistic probabilistic model for representation of near-fault ground motions is adopted in the design stage. The variability of future earthquake events is addressed by incorporating a probabilistic description for the ground-motion model parameters, leading to a design approach that is robust to probabilistic uncertainty. The methodology is illustrated through application to the base-isolated benchmark building with elastomeric and friction pendulum isolators and an array of regenerative force actuators. Skyhook control implementation is considered and an efficient scheme is presented for the clipping of the control forces in order to satisfy the actuator force constraints. The performance of the controlled system is evaluated under seven earthquake records using a number of metrics. Comparison with the performance of a similar network of viscous dampers is also discussed.

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