using mushroom shaped basements under buildings isolator in order to reduce the earthquake effect on structures

a new base isolation method for reducing the destructive effect of earthquake is proposed in this method mushroom shaped basements are used under structures as base isolation. these basements have spherical surface and are located on foundations. basements have pinned arms that are connected. when the length of the arm is less then the radius of spherical surface, the action of them is similar to a spring. in other words, when a displacement in a structure happens. a returning force is supplied to the structure and the stability of the structure is guaranteed. the specification of these springs is so that their stiffness can easily be set. as the stiffness is settable therefore the stiffness can be set in a way that firstly, the force applied to the structure will be acceptable, the maximum displacement will not exceed allowable limit. in this research the basements together with the structure were modeled as a one-degree freedom system of mass, spring and damper.