New Structural Seismic Isolation System

Abstract

New structural seismic isolation system named Spherical Foundation Structural Seismic Isolation (SFSSI) system which has been discovered and first prototyped on a 104 m height (26 storey) building example is presented. Creation of SFSSI system aimed to build structural seismic isolation system, of which period must be more than the predominant period ground motion of majority existing earthquakes including near-fault zones also. As known, classical period-dependent isolation systems and not isolated (fixed base-FB) buildings are vulnerable under long-period earthquakes and it is required to design resistant structural system components. For this purpose, a system has been realised as a structure with inverse pendulum system’s behavior. Structure foot base and foundation contact surface are formed in spherical appearance and they are separated by known Lead Core Rubber Bearing (LCRB) or Laminate Rubber bearing (LRB) isolators which are installed through spherical contact surfaces. Dampers are installed through base (structure foot) plate counter for controlling system’s response. This allows spherical foundation’s turning around gyration center through rubber bearing contact and keeps the same behavior to superstructure. In the SFSSI system it is possible to keep the natural period of the structure in a large interval, which is much more than predominant period of ground motion of the majority of the existing earthquakes including near-fault zones also. In this study, behavior of the both classical base-isolated building using LCRB and not isolated-FB building has been investigated under long-period ground motion. Obtained results are compared with SFSSI system with the same stiffness and equivalent damping and number of LCRB which was installed on spherical foundation. It was shown that, SFSSI system deprived from known deficiency period-dependent isolation systems and it is the progress of the new type earthquake-resistant structures. SFSSI system exhibits improved Roly-poly (‘Haciyatmaz’, ‘Okiogary-Koboshi’) behavior. We believe that as Roly-poly, structures with SFSSI system will symbolize the ability to have success overcome adversity, and recover from misfortune.