2019 CSCE Annual Conference - Laval (Greater Montreal) Conference
Dr. Zhen Cai, National Research Council Canada
Dr. Reza Fathi-Fazl, National Research Council Canada
A large number of existing buildings in Canada can potentially suffer severe damage or collapse in the event of strong ground shaking. The assessment and mitigation of seismic risk in large portfolios of existing buildings presents technical and economic challenges to building owners. To address these challenges, the National Research Council Canada (NRC) developed in the 1990s a series of manuals and technical guidelines for seismic screening, evaluation, and upgrading of existing buildings, based on seismic risk guidelines in the United States (FEMA 154, FEMA 178, and FEMA 273) and in accordance with the 1990 edition of the National Building Code of Canada. The NRC manuals and guidelines have been instrumental in the seismic screening and evaluation of existing Canadian buildings for over 20 years. However, these documents do not reflect the changes in the National Building Code, including the seismicity and more stringent seismic design requirements. To address these shortcomings, the NRC has recently developed a seismic risk management framework that includes a multi-criteria and multi-level seismic risk management framework, which includes a Seismic Risk Screening Tool for identifying and prioritizing existing buildings with potential unacceptable seismic risk for further detailed seismic evaluation. The screening tool consists of methodologies for seismic risk screening of the structural system and non-structural components of existing buildings. The main objective of the tool is to identify and prioritize buildings with potential unacceptable seismic risk for further detailed seismic evaluation. The seismic risk of the structural system is based on the probability of building collapse and identified consequences of failure to life safety. The global seismic risk of non-structural components is qualitatively assessed based on seismic demand and key parameters affecting the seismic response of the components. Calculated structural and non-structural scores are compared with corresponding structural and non-structural thresholds, which are function of consequence of building failure. The scoring systems reflect the expected seismic risk for different seismic zones, i.e. acceptable seismic risk in Very Low and Low seismic zones and unacceptable seismic risk in High and Very High seismic zones.