Seismic Control of Benchmark Highway Bridge Using Semi-active Control System and Self-Tuning Fuzzy Controller

During the past few decades, extensive damage to structures due to severe earthquakes has encouraged structural engineers to use seismic control systems. Bridges are critical nodes in transportation networks and must remain utilizable after an earthquake. Therefore, a higher level of performance with less structural damage is required for bridges. In the present research, a self-tuning fuzzy controller (STFC) with semi-active MR dampers is proposed to reduce the seismic response of the benchmark highway bridge. This controller combines the advantages of fuzzy inference systems and adaptive control in a two-part control architecture consisting of primary and secondary controllers. More specifically, the self-tuning mechanism considers different characteristics of seismic excitations and structural conditions to increase the controller efficiency in different situations. The role of the primary controller is to determine the input damper voltage, while the secondary controller adjusts them online according to seismic excitations and structural conditions. In order to increase the effectiveness of the proposed controller, the output parameters of the Sugeno fuzzy inference systems in the primary controller were set by a genetic algorithm. Finally, the proposed STFC was employed under several patterns from actual benchmark earthquakes and the evaluation criteria of a seismically excited highway bridge benchmark were determined. The obtained results exhibited a higher ability of the proposed self-tuning fuzzy controller to improve the highway bridge benchmark criteria, especially those related to damage such as displacement at bridge midspan, deformation of bearings, curvature of bent columns, and dissipated energy at the structural members. On the other hand, the evaluation criteria suggest that the proposed self-tuning fuzzy controller could reduce seismic responses under different earthquakes and adapt to different seismic excitations. Moreover, comparing the proposed controller with another adaptive fuzzy controller indicates the higher efficiency of the proposed STFC approach, especially in improving damage-related performance measures.