Resiliency Framework for Seismic Risk Assessment and Management of Buildings

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The Insurance Bureau of Canada (IBC) estimation of earthquake induced damage to core public infrastructure (CPI) in western (British Columbia) and eastern (Ottawa-Montreal-Quebec City corridor) is in the order of $60-$75 billion. The IBC’s report further highlighted that with the incorporation of resiliency, the damage can significantly be reduced. Seismic resiliency of a system has been associated with reducing chances, absorbing and recovering quickly after a shock. CPI, including roads, bridges, transit, and water and wastewater systems, are essential to ensure health, safety, economic security and overall quality of life in Canada. The long term objective of this research program is to develop a resiliency framework for Canada’s CPI. The framework will incorporate the failure of each CPI and also dependencies and cascading effects. Furthermore, the framework will incorporate multiple shocks, e.g. mainshock-aftershock earthquakes. In this proposal, the resiliency framework is applied for different Canadian building types, with focus on reducing impact of an earthquake and improving the recovery by quantifying the downtown in the consequence of failure. To achieve this objective, the research goals are categorized into the following three themes: Theme A) Develop building vulnerability assessment and robustness index framework for existing buildings by accounting for different uncertainties and building irregularities (Projects A1 and A2). Based on the level of information available a building vulnerability assessment guidelines that incorporate model selection and analysis technique will be developed. Finally, a new Canadian Building Code Effectiveness Grading protocol will be developed and applied to over 600 Canadian cities (as provided in the building code). Theme B) Develop an integrated retrofit optimization and selection framework. This framework will enable the decision makers to carry out scenario analysis for different retrofit alternatives and select the desired retrofitting technique (projects B1, B2 and B3). The retrofit resource allocation and optimization will be undertaken at two different resolutions (city and building levels) and involve simulations for different hazard levels. In this research, a derivative-free approach that guarantee of optimality will be used. The challenge of decision making is further compounded due to the uncertainties associated with hazard assessment and knowledge of the decision making process for specific alternatives. Theme C) Develop a framework that will quantify both structural and non-structural failures within the risk assessment and management framework. This framework will account for the likelihood of failure through fault-tree and consequence of failure through event-tree analyses. This is denoted as a bow-tie diagram in the risk literature. Thus, the building vulnerability tool from Theme A and retrofitting assessment framework from Theme B will be integrated into this bow-tie diagram. Downtime will be quantified as one of the consequence of failure that addresses the recover quickly component of the resiliency framework (project C1). This research will lead to an advanced understanding of seismic risk assessment and significantly better management of civil infrastructure systems. The knowledge and understanding gained from this critical research will directly improve the risk assessment and management of existing buildings. This will have significant impact on Canadian society by improving the resiliency of our civil infrastructure systems.