A New Seismic Design Method for Steel Multi-Tiered Braced Frames

A seismic design strategy is presented to design the columns of multi-tiered steel braced frames. Minimum strength and stiffness requirements are introduced for the columns under the seismic loads. The proposed method aims at reducing the concentration of ductility demand in one of the tiers and, thereby, the in-plane bending moment demand on the columns and the ductility demand on the bracing members. Nonlinear static and dynamic analyses are performed to validate the design procedure. Moreover, detailed finite element analysis is carried out to investigate the stability of the columns. The results show that the proposed design method can efficiently reduce the column in-plane flexural demand and the brace ductility demand.