Department of Civil Engineering, Ferdowsi University of Mashhad, P.O. Box 9177948944-1111, Iran
In this study, the effect of active and semi active fuzzy logic controllers (FLC) on the damage imposed on steel structures considering structural uncertainties are investigated. Two FLCs are designed for controlling the actuators and controllable viscous dampers, as active and semi active devices, respectively. Fragility curves are used to show the probability of damage imposed on uncontrolled and controlled structures. They are developed in consideration with three performance levels specified in FEMA 356, including Immediate Occupancy (IO), Life Safety (LS) and Collapse Prevention (CP). For investigating the effect of structural uncertainties on the damage, fragility curves are generated separately considering deterministic and probabilistic parameters for the structure. To simulate the structure including the probabilistic parameters, Latin hypercube sampling is employed. Effectiveness of the controllers are illustrated and verified using the simulated response of a 3-story nonlinear benchmark building excited by several ground motions. To compare the performance of fuzzy controllers, fragility curves are also generated for the structure controlled by LQG and clipped-optimal controllers. Results show that FLCs can reduce the probability of damage significantly. Moreover, it is observed that the uncertainty in mass and yield strength have the greatest effect on the maximum drift of structure.