Research Reports

Seismic Hazard, Building Codes and Mitigation Options for Canadian Buildings

Authors:
Simon Foo
Nove Naumoski
Murat Saatcioglu

Department of Civil Engineering
University of Ottawa
Ottawa, Ontario, Canada

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Executive Summary

The extent of casualties and economic losses during recent earthquakes worldwide has been staggering, with loss of lives in the tens of thousands, and loss in economy in the billions of dollars. The February 28, 2001 earthquake near Seattle, which rattled buildings and occupants in Vancouver, could be viewed as a reminder to people living in Canada's most active seismic zone, the Pacific coast. However, other parts of Canada, such as regions along the St. Lawrence River and Ontario/Quebec border, are also potential sites for moderate to strong earthquakes. As a case in point, the 1988 Saguenay earthquake in Quebec was the strongest event in eastern North America within the last 50 years.

This study consists of three related documents dealing with the built environment and seismic aspects of building codes in Canada, primarily the 1995 National Building Code of Canada (NBCC). The consequences of recent earthquakes and their effects on the buildings have exposed a common concern: older buildings may be susceptible to significant damage. This in turn could result in traumatic loss of life and property and lead to a difficult and protracted recovery period both from a human and an economic perspective. Conversely, newer construction designed and built using more stringent code requirements may be less susceptible to significant damage.

In an effort to provide Canada's seismic protection community with a state-of-the-art knowledge base on the seismic hazard assessment and mitigation for buildings, three tasks were carried out within the scope of this project. These include a review of:

• variances in seismic requirements for existing buildings with respect to applicable codes and regulations in Canada,
  
• emerging technologies for the seismic retrofit of buildings; and
  
• current screening methodology.

Part A, which deals with "variances in seismic requirements for existing buildings," reveals that the codes and regulations in place for seismic protection of existing buildings are less stringent than the requirements for new construction. The report concludes that in order to prepare communities for seismic events, and maintain their sustainability through better readiness, proactive rather than reactive codes and regulations are needed. This can help improve seismic performance of existing buildings in Canada.

Part B, a "review of technologies," discusses seismic upgrade techniques as well as research issues concerning seismic retrofitting of buildings. Building seismic retrofitting is a relatively new activity for most structural engineers. The retrofitting of a building requires an appreciation for the technical, economic, and social aspects of the issue. Changes in construction technologies and innovations in retrofit technologies represent an additional challenge to engineers in selecting a technically, economically and socially acceptable solution.

Conventional upgrading techniques usually include the addition and/or strengthening of existing walls, braces, frames, and foundations. Adopting these techniques often leads to heavy demolition, lengthy construction time, reconstruction, and occupant relocation with all the associated direct and indirect costs. It is often the indirect costs, the environmentally hostile approach, and the inconvenience associated with conventional techniques that deter building owners and custodians from committing to seismic retrofit.

Part C reviews seismic "screening methodology," and is a review based on the 1993 NBCC seismic screening document and how it relates to building codes in Canada.

This three part document summarizes recent development efforts and innovative technologies for mitigation of a given building's seismic hazard susceptibility. Advanced materials, systems and techniques have been extensively investigated, and, to a lesser extent, applied in seismic retrofit projects. The current gap between research advances and application benefits is principally due to the lack of state-of-the-art knowledge bases available to both research and practicing engineers. As such, the benefits of utilizing innovative technologies as technically, economically and socially acceptable solutions for seismic hazard reduction have not yet been fully realized. This report is a first step in providing Canada's seismic protection community with a state-of-the-art knowledge base dedicated to seismic retrofit mitigation options for Canadian buildings.

Acknowledgments

This publication has been prepared for:

Office of Critical
Infrastructure Protection and
Emergency Preparedness

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This material is based upon work supported by the Directorate of Research and Development (DRD) in the Office of Critical Infrastructure Protection and Emergency Preparedness (OCIPEP), formerly Emergency Preparedness Canada, under Contract Reference No. 2000D020. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Office of Critical Infrastructure Protection and Emergency Preparedness.

©2001 Minister of Public Works and Government Services
Catalogue No.: D82-73/2002E-IN
ISBN: 0-662-32761-6