Seismic response and design of steel multi-tiered concentrically braced frames of the conventional construction category in moderate seismic regions of Eastern Canada

Abstract

This study examines the seismic behaviour of steel multi-tiered concentrically braced frames (MT-CBFs) of the conventional construction category (Type CC) in moderate seismic regions of eastern Canada and proposes a new seismic design method for such structures. A total of 32 prototype MT-CBFs part of a single-storey building are selected and designed in accordance with the 2019 Canadian steel design standard (CSA S16-19) provisions for Type CC structures, excluding the design requirements prescribed for frames taller than 15 m, namely the amplification of seismic forces varying by the frame height and the amplification of the column factored seismic force. Nonlinear response history analyses are then performed to examine their seismic response. The results confirmed that tiers experience limited lateral deformation, intermediate horizontal struts are required between tiers, and columns are subjected to combined axial force and bi-axial bending, which in some cases led to column buckling. The results are used to propose a new seismic design method in the framework of CSA S16.