A research project getting under way this fall, dubbed the "Three Little Pigs," is the first of its kind to analyze in real time how wind--up to Category-5 hurricane strength--takes apart light-frame structures.
The $7 million research project, carried out by the engineering department at the University of Western Ontario, is significant because it will be the first ever in which a full-sized mock building will be put through simulations of the gustiness and variability of real wind.
"The wind causes pressures, so what we're doing is replicating those pressures," said Greg Kopp, research team member and the university's Canada research chair in wind engineering.
Kopp compared these pressures to those that lift airplanes off runways. These same pressures batter structures in a windstorm.
Kopp suggested that insights from the experiment could impact how real buildings are put together.
"We definitely will have an impact with building codes," Kopp said. Not only will the engineers test how well the house stands up to wind, but also how wind-driven rain finds its way inside otherwise sealed structures--and how mold subsequently grows.
Researchers will also contemplate how human error in construction affects windstorm performance.
"We think we can also have a big effect with product testing," Kopp said. "Say it (a building product) passed some standard test. We can actually relate that to what that may mean in terms of real hurricanes and real wind loads."
The researchers have devised a system of about 100 fans connectable to the surface of the test building, along with a control system that allows researchers to vary the degree and "gustiness" of wind pressure at exact spots on the building. The fans can simulate up to Category-5 winds.
The team modeled how wind would act on the house by using a small-scale replica in a wind tunnel.
Starting this fall, the team will test their fans on single walls and windows. In spring 2007, they will turn the fans on the full-size structure. When sections get destroyed, the engineers will rebuild and retrofit them, and then repeat the razing. They plan to spend two years on the process.
"So we can gain as much possible information as we can from this one structure," Kopp explained.
The test structure is a two-storied, four-bedroom brick house, complete with a real heating and plumbing system. It's located in a 13,000-square-foot, sheet-steel hangar at the airport in London, Ontario, which is on the other side of Lake Erie from Cleveland.
As for those simulated Cat-5 winds, Kopp said he expects to use them for specific product tests. But as for the poor house, there might be no amount of retrofitting to help it survive Category 1 through 4.
"I'm not sure if this house will ever get there," Kopp said.
The project was launched with funding from the Institute for Catastrophic Loss Reduction, a joint venture of the university and insurance companies, and is now funded by the Canada Foundation for Innovation and the Ontario Innovation Trust.
September 15, 2006
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