Seismic force modification factors for the proposed 2005 edition of the National Building Code of Canada

This paper describes the proposed changes to the 2005 edition of the National Building Code of Canada related to the force modification factors. A description of the ductility- and overstrength-related force modification factors is given. The selection of the values proposed for these two factors for the various seismic force resistance systems is given in light of the design and detailing provisions that are specified in the Canadian Standards Association standards for steel, concrete, timber, and masonry building structures.Key words: buildings, ductility, earthquakes, force modification factors, overstrength, seismic.