Hybrid control of sliding isolated structures

The seismic response of buildings and bridges can be improved by isolating the structure with a seismic sliding bearings. Specialized passive devices are commonly used to complement these bearings, to control the displacement of the structure during large magnitude events, and to restrict a build-up of drift. Active servo-hydraulic actuators are used herein to supplement the conventional sliding bearings creating a hybrid active-passive protective system. The control system is capable of minimizing the inertial forces in the structure, while providing higher damping ratios and better displacement control when necessary. This paper presents three control algorithms for the hybrid system. Two of these algorithms are verified experimentally, and the third is verified with an analytical model. The results show that the hybrid system is capable of significantly improving the seismic response of the structure.