|The Triple PendulumTM bearing offers better seismic performance, lower bearing costs, and lower construction costs as compared to conventional seismic isolation technology. The properties of each of the bearing’s three pendulums are chosen to become sequentially active at different earthquake strengths. As the ground motions become stronger, the bearing displacements increase. At greater displacements, the effective pendulum length and the effective damping increase, resulting in lower seismic forces and bearing displacements.
The Triple PendulumTM bearing’s inner isolator consists of an inner slider that slides along two inner concave spherical surfaces. Properties of the inner pendulum are typically chosen to reduce the peak accelerations acting on the isolated structure and its contents, minimize the participation of higher structure modes, and reduce structure shear forces that occur during service level earthquakes.
The two slider concaves, sliding along the two main concave surfaces, comprise two more independent pendulum isolators. Properties of the second pendulum are typically chosen to minimize the structure shear forces that occur during the design basis earthquake. This reduces construction costs of the structure. Properties of the third pendulum are typically chosen to minimize bearing displacements that occur during the maximum credible earthquake. This reduces the size and cost of the bearings, and reduces the displacements required for the structure’s seismic gaps.