A Roof Isolation System with Variable Friction Dampers for Seismic Protection of Multistory Buildings

摘要

Using tuned mass dampers is a well known and effective way to protect buildings from earthquakes, winds and other types of dynamic excitations. Several structures all over the world provided with TMD have demonstrated enhanced behavior. Sometimes the tuned mass displacements relative to the roof is big enough, and in order to decrease it supplemental dampers are used. Another disadvantage of tuned mass dampers is that they contribute to the static loads acting on the building. A more effective way allowing similar improvement in structural dynamic response is implementation of roof isolation systems, which require no additional mass. The current study is aimed to investigate a roof isolation system incorporating variable friction dampers. The variable friction dampers have re-centering capacity and limit displacements of the isolated roof part relative to the upper floor diaphragm. A method for selection of the dampers properties is proposed. A numerical example has been carried out on a six-story frame building subjected to three natural earthquake records. It shows that a structure with the proposed system has an enhanced seismic behavior and proves the effectiveness of the VFD in limiting the isolated roof part displacements.