Fuzzy supervisory control of earthquake-excited cable-stayed bridges

A fuzzy supervisory control (FSC) technique is proposed for the seismic response control of cable-stayed bridges. The proposed technique is a hybrid control method, which adopts a hierarchical structure consisting of several sub-controllers and a fuzzy supervisor. The sub-controllers are independently designed in order to reduce the selected responses of a cable-stayed bridge and a fuzzy supervisor is introduced to modulate the pre-designed static gains into time-varying dynamic gains to improve seismic performance. In the design of the sub-controllers, shear forces and bending moments at the base of the towers, longitudinal displacements at the top of the towers, relative displacements between the deck and the tower, and tensions in the stay cables were selected as control variables. To demonstrate the effectiveness of the proposed strategy, example designs and numerical simulations were performed using a benchmark cable-stayed bridge subject to three historically recorded earthquakes. For comparison of the seismic performance, an optimally designed LQG system is also simulated for the benchmark bridge. The simulated results show that the FSC system can efficiently reduce the seismic responses of the cable-stayed bridge while maintaining lower control efforts.