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Aerodynamic Control of Long Span Suspension Bridges

Dr Xiaowei Zhao

School of Engineering, University of Warwick

We investigate the suppression of flutter and buffeting in long-span suspension bridges. Our approach is to control leading- and trailing-edge flaps that are fitted to a rigid sectional model of a contemporary suspended-span bridge. The flap control is responsive to movements of the bridge deck. The aerodynamic forcing is modeled using thin aerofoil theory. Passive mechanical controllers are proposed that operate the flaps so as to increase the critical wind speed for flutter, while simultaneous suppressing buffeting. The control system design problem is solving as a mixed H2/H optimization problem. The flap controllers sense the vertical velocity of the leading- and trailing-edge flap pivots and use these signals to produce control torques and adjust the flap angles accordingly. In the case that the leading- and trailing-edge mechanical controllers are identical, the control system becomes insensitive to the wind direction. The Akashi-Kaikyo bridge is used as a working example for the numerical simulation evaluation of the closed-loop system performance. We also conduct various wind tunnel experiments for the aerodynamic properties of a bridge-deck model, system identification and flutter & buffeting control systems.