First-Storey Isolation Concept for Multi-Performance Seismic Design of Steel Buildings

In this paper the design process of a first-storey seismic isolated steel frame building is developed within the framework of performance based seismic design. In detail the first storey seismic isolation is realized through the insertion of special hysteretic steel devices (called crescent shaped braces) which allows to satisfy pre-selected performance objectives. The basic idea of design process is the separation between the vertical and horizontal load resisting systems which allow to develop an optimized multi-performance seismic design. The design tools are based on the direct displacement based design procedures and capacity spectrum method, while the verification of the seismic performance of the designed building is obtained by mean of a set of non-linear time history analysis.