EACWE 5 Florence, Italy 19 th – 23 rd July 2009 Flying Sphere image © Museo Ideale L. Da Vinci Keywords: vibration control, MR dampers, tall buildings, wind loads, wind tunnel. ABSTRACT This paper presents response reduction of wind-induced vibrations in tall buildings using MR dampers. The dampers are implemented optimally using both internal and outer bracing systems to reduce the response of the building in the two lateral directions for both structural safety and human comfort concerns. MR dampers with internal bracing system are shown to be effective in one lateral direction where the building is behaving mostly in shear. For cantilever like vibrations, MR dampers with outer bracings are used. A proposed lever mechanism is used with the dampers to improve their performance. The proposed mechanism is shown to be very effective in reducing the capacity and number of dampers required. Semiactive decentralized bang-bang controller used with the MR dampers is shown to be effective in enhancing the performance of MR dampers over the passive-on case. 1. INTRODUCTION Vibrations in buildings are of increasing importance as the use of high-strength, light-weight materials, longer floor spans, and more flexible framing systems result in structures that are more Contact person: A.M. Aly, Politecnico di Milano, Via G La Masa 34, Milano, Tel: (+39) 0223998023 Fax: (+39) 0223998081 E-mail: aly.mousaad@polimi.it MR dampers with lever mechanism for response reduction in high-rise buildings under wind loads A. Zasso, A.M. Aly, F. Resta Politecnico di Milano – alberto.zasso@polimi.it – Via G La Masa, 1, Milano, Italy Politecnico di Milano – aly.mousaad@polimi.it – Via G La Masa, 34, Milano, Italy Politecnico di Milano – ferruccio.resta@polimi.it – Via G La Masa, 1, Milano, Italy