Effect of Earthquake on Fire Protection Systems Kyung Hoon Sun Dept. of Civil and Environmental Engineering Michigan State University

Damage agents of an earthquake Fault rupture Shaking Landslides Release of hazardous materials Tsunami Liquefaction By definition, shaking is the predominant damage agent. But, building characteristics, density, meteorological condition and other factors may combine, Fire is the predominant damage agent, called Fire Following Earthquake or Post Earthquake Fire

Historical Fire Following Earthquakes The fire following the San Francisco earthquakes in 1906 The fire following the Tokyo earthquakes in 1923

Major Factors Governing Damage Earthquake intensity : Shaking intensity has much influence on the built structures (MM intensity scale) Subsoil Properties: Dynamic properties of the subsoil may have an important influence Ground condition : Effect on the seismic consistency of underground services, such as water, gas or oil The building configuration and structural characteristics: Flexible buildings, more deflection, stiff >> more acceleration The age of the building: Before and after the earthquake engineering, significant difference

Damages caused by FFE Structural damage Modern buildings are able to stand at high earthquake intensity levels up to MM9 without having significant structural damage. Smaller levels of structure damage may cause fire Significant cracking or movement that may allow smoke penetration through walls and slabs Dislodging of fire resistant coatings from structural element Damage to stairs may deter evacuation

Damages caused by FFE Non-structural damage Walls, partitions and external glazing are vulnerable to earthquakes Fire separations may suffer major cracking The loss of exterior glazing changes the ventilation factors  may allow larger fires Fire stopping in seismic joints may be dislodged  become useless Dislocation of ceiling systems and shelving  cause injury and delay evacuation

Damages caused by FFE Active systems damage Lifeline system damage Smoke detectors, circuits and panels on alarm and control systems may not be able to function properly All the fire safety devices without back-up power will be vulnerable to failure. Sprinkler systems can be damaged from inertia loads on the suspended pipe-work, movement across seismic joints and impact with suspended ceilings Lifeline system damage Damage to the ground transportation system Failure of the supply system, pump and reservoirs Major difficulty in operating rescuing, fire fighting and gaining access for medical aids

Prediction of damage Based on data from observed earthquakes Assessment of building systems is usually generic in nature. The investigators generally considered only those earthquake effects that may bring urban conflagration Not many examinations are done to predict damage to specific building elements and systems The increasing availability of knowledge on performance of individual elements  US and Japan develop damage assessment methods for individual buildings based on the weakness of the particular elements and systems in the building. Performance evaluation for building design: Considers the individual characteristics of each building rather than being limited to global assessment categories

Performance codes for FFE Requires each potential event to be considered specifically Porter et al.(2001): Developed a wider performance evaluation model that considers both active and passive systems. Results of testing to predict the vulnerability of wood framed partitions and glazing to deformations Sekizawa et al. (2000): Proposed a probabilistic method to assess post earthquake fire spread within a building. Based on observed damage in a number of locations. Inputs: building geometry, construction type, fire safety systems, fire load density and growth rate, and ground acceleration. Compute the probability of ignition, active system failure, passive system failure, and intervention  Output is in the form of an expected fire spread area. Feeney (2001): Risk analysis on sprinkler effectiveness in multi-level steel buildings. The main purpose is to study probability of structural failure. Report used available statistical data on probability of earthquake occurrence, fire ignition, sprinkler operation, sprinkler control of the fire, and integrity of passive fire protection to determine the probability of an adverse effect on the structure

Analysis HE 240B steel section Exposed to ASTM E119 Fire on three sides No fire protection Failure T =550oC 17mm 10mm 240mm 750 sec

Analysis The bending moments with fictitious earthquake load applied are higher than the ones in normal fire incidence situation The failure of the structure would be faster than the expected failure time It is important to reduce the fire or apply minimum passive fire protection to the steel sections in order to increase critical time

Conclusion Many fire safety systems, such as sprinklers, smoke detectors, can be damaged by significant earthquake and may not function properly Inoperative fire safety system could cause more severe damages on the structure, and life. In order to prevent from catastrophic disaster due to post earthquake fire, performance based design is now world widely spread and being developed Still significant amount of work is remained for establishing a universally accepted design methodology for fire following earthquake

Thanks ?