- Author
-
Robertson, J. N.
- Title
- Accounting for Fire Following Earthquakes in the Development of Performance Based Building Codes.
- Coporate
- University of British Columbia, Vancouver, Canada
- Report
-
THESIS
October 1998
88 p.
- Keywords
-
earthquakes
|
performance based codes
|
building codes
|
reliability
- Identifiers
- historical earthquakes; Canada's seismic regions and vulnerability; application of reliability analysis techniques
- Abstract
- This paper reviews the occurrence of fires following earthquakes and assesses the significance of such fires in the development of performance based building codes for application in areas of known seismic activity. Fires following earthquake represent a significant fire hazard to large urban areas such as the west coast of North America and Japan. The two largest peacetime urban fires on record were caused by conflagrations following major earthquakes (1906 in San Francisco and 1923 in Tokyo). More recently , the 1989 Loma Prieta earthquake, the 1994 Northridge earthquake and the 1995 Kobe earthquake in Japan have heightened awareness of the continued vulnerability of densely populated urban areas to fire following an earthquake and the likelihood of these fires developing into major conflagrations. This paper examines the fundamental risk factors which influence the growth of these fires and their development into conflagrations. The presence of these risk factors in recent earthquakes occurring in the USA and Japan are compared to the conditions prevailing in earthquakes which occurred in the early part of this century, and it is concluded that the relatively rapid industrialization of both North America and Japan continues to present and further compound the presence of risk factors associated with large scale earthquake induced conflagrations. Fires following an earthquake are characterized by a significantly impaired fire fighting capability, a partial or total loss of lifeline systems together with increased risk of ignition, often in the vicinity of gas leaks or fuel spills, In this scenario it is critical that any design methodology recognize the potential for systematic loss of functionality of lifeline services, significant impairment of fire fighting response capability, and multiple ignition scenarios. The implications of the post earthquake fire scenario for the development of performance (or objective) based fire and life safety building codes is examined, with specific reference to the proposed development and implementation of a performance based code for Canada. Currently, the Canadian Codes Commission is committed to developing a leadership position in North America with respect to performance based codes and is moving rapidly ahead with its development of an objective based code in its current code development cycle. This code is currently scheduled to be released by the year 2003. The USA and Japan are similarly making the transition toward performance based codes. The International Codes Commission (ICC) and the National Fire Protection Association (NFPA) are developing performance based codes and various technical societies such as the Society of Fire Protection Engineers (SFPE) and the Structural Engineers Association of California (SEAOC) are developing performance based analysis and design procedures. For instance, SEAOC's Vision 2000-Performance Based Seismic Engineering of Buildings adopts a general objective that "at specified levels of ground motion and with defined levels of reliability, the structure will not be damaged beyond certain limiting states." Performance based codes will offer designers significant flexibility in their designs and more cost effective techniques for achieving fire and life safety objectives, particularly in the rehabilitation of existing buildings which are not adequately addressed in existing codes. It is likely therefore that more effective use will be made of current and emerging technology in tire detection and suppression systems. It is important in adopting such solutions, that the exposure of buildings to the hazards of tire following earthquakes is not inadvertently increased to an unacceptable level. Various strategies for assessing the risk factors associated with fire following earthquakes are explored and it is recommended that performance based fire and life safety codes incorporate explicit objectives to control and limit the vulnerability of large urban areas to the uncontrolled spread of tire following an earthquake. It is considered that this approach will minimize the risk of adopting design solutions which pose unacceptable hazards in a post earthquake scenario although meeting established objectives for fire and life safety in the more typical tire scenario of an individual fire event occurring under normal detection and suppression conditions.