Self-Centering Seismic Isolation Bearing

Self-Centering Seismic Isolation Bearing for Bridges Using Shape Memory Alloy Bars and Variable-Depth Slider Friction

This technology is installed between bridge superstructures and substructures. It consists of a slider inserted into the longitudinal groove of the bottom plate and multiple shape memory alloy bars connecting the top and bottom plates. It absorbs energy through friction during earthquakes and uses the restorative force of the shape memory alloy bars to return to its original position.

While seismic isolation design is becoming standard for domestic bridges and facilities that lack earthquake preparedness, existing hybrid seismic isolation devices make it difficult to predict energy absorption and horizontal displacement between plates based on earthquake wave types and magnitudes. Furthermore, they often struggle to maintain their self-centering performance over time in harsh environments with extreme temperature fluctuations or frequent seismic activity.

This technology is designed so that as the shape memory alloy bars bend during relative movement, the gap between the plates decreases and the slider insertion depth increases, causing the contact area—and thus friction—to increase incrementally, making energy absorption and displacement predictable. Friction can be adjusted by selecting fixed blocks, and auxiliary restorative force can be added using moving blocks and elastic elements in the rail grooves. Suitable for new construction and retrofitting of highway and railway bridges, overpasses, and bridges in seismic zones, it allows the bearing to self-center after an earthquake without requiring repairs.

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Key Features:

• An upper plate coupled to the superstructure and a lower plate coupled to the substructure, featuring a longitudinal insertion groove on its top surface.
• A slider with one end coupled to the upper plate and the other inserted into the first groove, where its sides contact the lower plate and the contact area adjusts based on insertion depth.
• Multiple primary shape memory alloy bars with both ends inserted into the coupling grooves of the top and bottom plates to provide restorative force during longitudinal relative movement.
• An operating mechanism where the bending of the primary shape memory alloy bars reduces the plate gap and increases the contact area until the slider base meets the groove floor.

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