Optimal damper characteristics of ATMD for buildings under wind loads

Abstract

Recently, Ankireddi and Yang derived analytical expressions for the damper characteristics and the controller feedback gain coefficients for the design of an active tuned mass damper system (ATMD) in reducing the first-mode response of buildings under wind loads. These expressions allow one to determine the optimal feedback gains that define the control force. The derivation is based on the simplifying assumption of white-noise excitation to represent the wind loads. This paper examines the accuracy of their expressions when applied to more sophisticated mathematical models for wind loadings. The Hrms norm control technique, in conjunction with the GRG algorithm, is used to obtain the optimal values of these damper characteristics and the controller feedback gain coefficients under both along-wind and across-wind excitations. The results furnished by Ankireddi and Yang expressions are then compared with the present results. For general application, the study covers a wide range of rectangular section buildings by considering representative buildings of very short to very tall ones. It was found that the expressions were reasonably accurate in the case of along-wind excitation. However, the expression for the damper frequency ratio has to be significantly modified for the case of across wind excitation. The final expressions given herein should be useful in giving the optimal feedback gains for the control force to be used in the design of ATMD system for vibration control of structures under along- and across-wind excitations.