Quake test exposes big fire threat
- San Diego Union-Tribune6 a.m.March 16, 2013
The powerful earthquake simulations that UC San Diego ran on a five-story building last spring caused damage that allowed fire and smoke to spread in ways that could have prevented people from escaping if the event had been real, says a review of one of the largest seismic tests in American history.
The experiment reaffirmed that fire can be a horrific after affect of an earthquake, and it gave scientists an unusually vivid look at how smoke can spread throughout such building features as elevators, staircases and exits.
"The upshot is that the combination of damage from the shaking and the resulting spread of fire and smoke leads to a higher potential loss of life," said Brian Meacham, a researcher at the Worcester Polytechnic Institute (WPI) in Massachusetts, and one of the project's lead investigators.
UCSD collaborated with other schools and agencies in designing and building a 75-foot tall, 1.4 million pound structure that was placed on an outdoor shake table at the test site that the university's Jacobs School of Engineering operates at Scripps Ranch. The building was outfitted with the kind of elevator, ventilation and fire protection systems that would be found in modern structures. Part of the tower also was turned into a mock hospital, featuring a medical suite and an intensive care unit.
The tower was then subjected to shaking that replicated a range of earthquakes, from the magnitude 6.7 Northridge quake in 1994, which killed about 60 people, to the 7.9 Denali quake in 2002. The building sat atop base isolators, or shock absorbers, that limited damage. But the newly released study says that following the largest simulated earthquake the structure's "staircase failed and the elevator became unusable."
After the shaking portion of the tests, WPI set fires in the building and monitored the movement of flames and smoke on the scores of cameras that had been placed throughout the structure. The cameras revealed that "damage to walls and ceilings created cracks and openings that allowed smoke and flames to spread," WPI says in a statement. "Doors got stuck (both open and closed), cutting off evacuation routes ... (And) the elevator shaft helped smoke and fire travel to the building's upper floors."
A summary of the fire experiments adds that "sprinklers, heat-activated fire doors and special materials designed to stop fires performed well."
Tara Hutchinson, the UCSD engineer who led the experiments, said "these tests (were) able to expose the building to very extreme earthquake demands, well above the design earthquake, creating a state of near instability of the building. The measured data will provide an immense impact on the field of earthquake engineering. First, because the margin of safety against instability can be evaluated and the limits of the building were pushed. Second, because numerical models, including those being used by design engineers in daily practice, can be evaluated against this data set."
Meacham agrees, saying the tests "give us an opportunity to engineer more resilient buildings that would perform better in the future."
Source: http://www.utsandiego.com/news/2013/mar/16/earthquake-fire-buildings-destroy-testing/--
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