A Hybrid Sliding Isolation System with Controllable Friction Bearings

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Recently, a hybrid sliding isolation system employing computer-controllable friction bearings has been developed and proven to be more effective in controlling the seismic response of a single-degree-of-freedom system than the corresponding conventional passive sliding system. This proposed research intends to extend the applicability of this hybrid isolation system to multistory buildings by conducting a series of analytical and experimental investigations to develop an improved isolation system design. Analytical work will involve development of two control algorithms and computer simulation studies with different structural and isolation system parameters and different input motions. The experimental work will involve shaking table laboratory test on the proposed computer controllable isolation devices. The hybrid sliding isolation systems are more advantageous over the conventional passive systems in that they are more effective for earthquakes with a broad intensity range, and tend to be more robust. However, to fully implement such a system with confidence in practice, there appear to exist several major technical and practical problems that are yet to be overcome. The proposed research will develop: (1) improved friction controllable bearings with proper consideration of the problems of the possibility of uplifting and its prevention, choice of the proper materials for sliding interface, chamber pressure control, energy supply, and system maintenance, (2) robust control algorithms to satisfy requirements for simultaneously controlling three-dimensional multitudinous responses, such as floor acceleration, interstory deformation, and sliding displacement, and to prevent excessive overturning moment and uplifting problems associated with buildings, and (3) a unified computer codes package to conduct simulation studies of isolation performance on various building models under different earthquake excitations. The laboratory tests for component performance and scaled building model tests using a shaking table as well as the redesign of systems incorporating the changes suggested by the experimental results will also be performed in this study. The proposed research will resolve the remaining technical as well as practical problems existing with the innovative hybrid sliding isolation system - thus paving the way for its broad applications in building structures constructed in active seismic areas.