QUESTION: (SUMMER2016) In National Building Code of Canada 2015, the period dependant Site Coefficient F(T), used for determination of seismic Design Spectral Accelerations, has replaced Site Coefficients Fa and Fv. CSA Standard S16-14, however, continues to reference Site Coefficients, Fa and Fv. Is S16-14 out of step with NBC 2015?
ANSWER: CSA S16-14 is compatible with NBC 2015. In S16-14, coefficients Fa and Fv, appear in two expressions: the short-period specified spectral acceleration ratio, IEFaSa(0.2), and the one-second specified spectral acceleration ratio, IEFvSa(1.0). Certain values of these quantities serve as triggers for more stringent requirements whereas other values set the conditions for relaxation. Although F(T) has replaced Fa and Fv for the purpose of determination of Design Spectral Accelerations in NBC 2015 the Code retains the expressions IEFaSa(0.2) and IEFvSa(1.0) as triggers. As defined in Sentence 4.1.8.4. (7) of NBC 2015, Fa = F(0.2) and Fv = F(1.0). Ideally, F(0.2) and F(1.0) should also replace Fa and Fv respectively in these trigger expressions. This was not possible in the 2015 code cycle for the following reason: In order to be considered for adoption by NBC 2015, CSA material design standards, S16, A23.3 etc., must be published in 2014. However, changes proposed for NBC, including the period dependant Site Coefficient F(T), could not be finalized in time to meet the publication schedule for the CSA standards.
QUESTION: (FALL2012) When designing bolted connections, are seismic loads considered to be static or cyclic?
ANSWER:The Seismic Corner article entitled “Bolted Connections for Seismic Applications” in CISC publication, Advantage Steel No. 31 (Summer 2008), outlined the requirements for bolted connections for seismic applications in accordance with S16-01. The article is available at: https://cisc-icca.ca/ciscwp/product/advantage-steel-no-31/
In NBC 2010 and S16-09, the building height restriction for Conventional Construction where the specified short-period spectral acceleration, IEFaSa(0.2), exceeds 0.35 has been increased. The above mentioned requirements for bolted connections also apply to these taller structures of Conventional Construction.