SEMI-ACTIVE FUZZY CONTROL OF STRUCTURES SUBJECTED TO NEAR-FAULT GROUND MOTIONS HAVING FORWARD DIRECTIVITY AND FLING STEP USING FRICTION DAMPING SYSTEM WITH AMPLIFYING BRACES (FDSAB)

Abstract

In this paper, the consequences of well-known characteristics of near-fault ground motions, forward directivity and fling step, on the seismic response control is investigated. An integrated fuzzy rule-based control strategy for building structures incorporated with semi active friction damping system with amplifying braces (FDSAB) is developed. The membership functions and fuzzy rules of fuzzy controller were optimized by Genetic Algorithm (GA). The main purpose of employing a GA is to determine appropriate fuzzy control rules as well to adjust parameters of the membership functions. Numerical study is performed to assess the effects of near-fault ground motions on a building that is equipped with FDSABs. To demonstrate the effectiveness of the fuzzy logic algorithm, it is compared with that of a conventional linear quadratic regulator (LQR) controller, while the uncontrolled system response is used as the base line. Results reveal that the fuzzy logic controller with FDSAB is capable of improving the structural responses and is promising for reducing seismic responses during near-fault earthquakes. It is also shown that, the near-fault earthquakes require much more control force than the far-field earthquakes and result in less response mitigation.