Cyclic behaviour of triple friction pendulum isolators with elliptical surfaces

The geometry of triple friction pendulum seismic isolator surfaces was hypothetically changed from spherical to elliptical and force–displacement equations were derived for all motion stages. The effect of changing the elliptical surface diameters on the force–displacement diagrams and the amount of dissipated frictional energy was also investigated for separate hypothetical cases. According to the diagrams obtained from the sliding stages, the behaviour of isolators with elliptical surfaces in medium and large displacements is completely non-linear and can provide the possibility of achieving special performance for this range of input excitations to the structure.