Seismic response of concentrically braced dual steel frames

Concentrically braced steel frames are one of the most commonly used structural systems because of their structural efficiency, simplicity to analyze and design, and ease of construction and repair. Canadian design codes provide specifications for their design under seismic loading based on the large amount of knowledge related to their seismic response accumulated over the past two decades. This paper examines the impact of a dual system with a moment resisting frame acting in parallel with the concentrically braced frame. Four different frames were designed in accordance with the National Building Code of Canada and CSA-S16.1-M89, and their inelastic responses are studied under the action of both monotonically increasing load and seismic load. The relative strengths and stiffnesses of the frames comprising the dual systems were varied. The ductility demands on members, and overall building deflections and storey drifts, were examined under the action of ten earthquake records. It is concluded that impro...