Canadian Seismic Design of Steel Structures

Canadian Seismic Design of Steel Structures

Design of Steel Structures of the Canadian Standards Association (CSA) governs the design of the majority of steel structures in Canada. Clause 27 of the standard includes the earthquake design provisions for seismic force resisting systems for which ductile seismic response is expected. Technical changes and new requirements have been incorporated in the 2009 edition of CSA S16, including modifications of the expected material properties for HSS members, consideration of protected zones, definitions of brace probable compressive and tensile resistances for capacity design and special requirements for braces intersecting columns between floors for concentrically braced steel frames, new seismic provisions for buckling restrained braced steel frames, design and detailing requirements for built-up tubular ductile links in eccentrically braced steel frames, changes to the requirements for ductile steel plate walls and for plate walls with limited ductility, including allowances for perforations and corner cut-outs in infill plates, and special provisions for steel frames of the Conventional Construction category above 15 m in height. These modifications were developed in parallel with the 2010 National Building Code of Canada (NBCC). The paper summarizes the new CSA S16-09 seismic design requirements with reference to NBCC 2010.

Basic capacity design provisions are given in CSA S16 to ascertain that minimum strength hierarchy exists along the lateral load path such that the intended ductile energy dissipation mechanism is mobilized and the integrity of the structure is maintained under strong ground shaking. In the design process, the yielding components of the SFRS may be oversized compared to the specified design seismic forces, as would be the case when drift limits, minimum member sizes or non-seismic load combinations govern the design. In this case, it is specified both in NBCC 2010 and CSA S16 that the design forces in capacity-protected elements need not exceed those induced by a storey shear determined with RoRd = 1.3. This upper bound essentially corresponds to the elastic seismic force demand reduced by 1.3, recognizing that nonyielding components will likely possess minimum overstrength. This 1.3 reduction factor only applies if the governing failure mode is ductile, and RoRd = 1.0 must be used otherwise.

This file contains formatted spreadsheets to perform the following calculations:
 - Section 1: Area of equivalent diagonal brace for plate wall analysis (Walls).
 - Section 2: Design of link in eccentrically braced frames (EBF).
 - Section 3: Design of Bolted Unstiffened End Plate Connection (BUEP).
 - Section 4: Design of Bolted Stiffened End Plate Connection (BSEP).
 - Section 5: Design of Reduced Beam Section Connection (RBS).
 - Section 6: Force reduction factor for friction-damped systems (Rd_friction).

 Additionally, this file contains the following tables:
 - Valid beam sections for moment-resisting connections (B_sections).
 - Valid column sections for moment-resisting connections (C_sections).
 - Valid bolt types for moment-resisting connections (Bolts).
 - Database of properties of all sections (Sections Table).


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