Comparison of Triple Pendulum and Single Pendulum Bearing Sizes and Responses to Earthquake Motion
 
Single Pendulum Bearing Single Pendulum Bearing
Single Pendulum Bearing
Center Position
Single Pendulum Bearing
Maximum Credible Earthquake
 
Triple Pendulum Bearing Inner Pendulum Motion Service Level Earthquake Pendulum Motion Pendulum Motion
Triple Pendulum Bearing
Center Position
Inner Pendulum Motion
Service Level Earthquake
Lower Pendulum Motion
Design Basis Earthquake
Upper Pendulum Motion
Maximum Credible Earthquake
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The Single Pendulum bearing maintains constant friction, lateral stiffness, and dynamic period for all levels of earthquake motion and displacements. In the Triple PendulumTM bearing, the three pendulum mechanisms are sequentially activated as the earthquake motions become stronger. The small displacement, high frequency ground motions are absorbed by the low friction and short period inner pendulum. For the stronger Design Level Earthquakes, both the bearing friction and period increase, resulting in lower bearing displacements and lower structure base shears. For the strongest Maximum Credible Earthquakes, both the bearing friction and lateral stiffness increase, reducing the bearing displacement. When designed for a severe Maximum Credible Earthquake, the plan dimensions of the Triple PendulumTM bearing are approximately 60% that of the equivalent Single Pendulum bearing.
 
Single Pendulum Operation Triple Pendulum Motion
Single Pendulum Force Displacement
Hysteretic Loop
Triple Pendulum Force Displacement
Hysteretic Loop
 
     
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