An Innovative Steel Braced Frame System for Controlled Self-Centring Elastic Seismic Response of Low-Rise Steel Building Structures

An innovative steel braced frame system is introduced that is designed and detailed to exhibit an elastic self-centring hysteretic response and achieve damage-free seismic response for low-rise building structures. The system is implemented in the first storey of buildings so that all seismic-induced deformations intentionally develop in that storey to obtain a seismic response similar to that offered by base isolation systems. The proposed system is first described together with a design approach that is based on the single-mode analysis method widely adopted for the design of base isolation systems. The system is applied for two- to three-storey office buildings located in the high seismicity region of Vancouver, British Columbia, Canada, where the seismic hazard is contributed by shallow crustal, deep in-slab, and interface subduction earthquakes. Nonlinear response history analysis is performed under site representative ground motion records to verify the seismic performance of the proposed system. The study shows that the system can exhibit enhanced seismic performance in terms of peak lateral displacements and peak horizontal floor and roof accelerations, with no structural damage nor residual deformations. The results also suggest that peak lateral displacements can be reliably predicted using the simple single-mode method for base isolation systems.