Control of Seismic Response of Bridge Structures Using Variable Dampers

This study demonstrates, by way of numerical simulation, the potential utility of variable dampers for controlling structural response under seismic loads. Standard control theory is difficult to apply in a straightforward fashion in this case because the equation of motion includes the damping coefficient, which needs to be controlled instantaneously. The equation is nonlinear in the sense that the control uses feedback information involving the structural response itself. A bang- bang control and instantaneous optimal control algorithms are developed to control the damping coefficient. The effects of these control algorithms on the reduction of absolute acceleration of the girder and relative displacement between the girder and piers are examined for girder bridges. Promising results are obtained in reducing seismic responses.