NONLINEAR ADAPTIVE CONTROL OF BUILDING STRUCTURES WITH ELASTOPLASTIC BEHAVIOR OF ELEMENTS UNDER SEISMIC MOTION

One of the challenges in application of semi-active control strategy in building structures is their performance during extreme earthquakes. Indeed, when seismic forces are more than the capacity of structural elements or smart dampers, their dynamic behavior changes from an initial assumed linear model. Further concerns are; the high degrees of freedom of structures and various uncertainties in mathematical model and control devices. Adaptive Controllers (AC) because of their capability to modify their own operations independently are considered as one of the solutions for this problem. Among different algorithms, the Simple Adaptive Control (SAC) method with a nonlinear extension is a proper one for a time-variant system when the stiffness matrix is not consistent with time.In this paper, the efficiency of SAC method and its nonlinear extension (Nonlin-SAC) are investigated in a benchmark building equipped with MR dampers. In this 20-story steel frame, inelastic behavior of beams and columns are simulated by a bilinear hysteretic model in plastic hinges. The efficiency of two adaptive algorithms (SAC and Nonlin-SAC) are investigated when the structure is excited by earthquake ground motions at two different hazard levels.The results indicate that both SAC and Nonlin-SAC methods appropriately reduce the seismic response of the structure. In higher levels of ground motion, Nonlin-SAC has superiority special in reducing floors’ acceleration. By increasing the ground motion level, the number of saturated dampers is increased, and the efficiency of Nonlin-SACM is reduced, and approaching to SACM.

Keywords:

Nonlinear adaptive control , SACM , Plastic hinges , MR damper