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Giant Lab Replicates Category 3 Hurricanes
Pickens writes "The WSJ reports that a new $40 million research center built by the Institute for Business & Home Safety in Richburg, SC features a massive test chamber as tall as a six-story building that can hold nine 2,300-square-foot homes on a turntable where they can be subjected to tornado-strength winds generated by 105 giant fans to simulate a Category 3 hurricane. The goal is to improve building codes and maintenance practices in disaster-prone regions even though each large hurricane simulation costs about $100,000. The new IBHS lab will be the first to replicate hurricanes with winds channeling water through homes and ripping off roofs, doors and windows. The new facility will give insurers the ability to carefully videotape what happens as powerful winds blow over structures instead of relying on wind data from universities or computer simulations. The center will also be used to test commercial buildings, agriculture structures, tractor-trailers, wind turbines, and airplanes."
It does seem a very odd description, more likely to have crawled out of somebody's imagination than the numbers; but my understanding is that wind speeds vary a great deal under tornado conditions, which means that it is probably accurate, albeit in a way that is either irrelevant or actively misleading.
The actual cone of the tornado is extremely fast, quite powerful, and is where all the crazy stuff happens(large objects being lifted, spare I-beams getting shoved neatly through trees, etc.) Surrounding that is an area of air disturbance, with strength decreasing as you get further out.
Now, if they would just test homes made out of straw, sticks, and bricks and see if in fact, a straw house can be reinforced to withstand big bad wolf strength winds.
RIP America
July 4, 1776 - September 11, 2001
Sucks or blows, whatever, as long as there's swallowing that's all that matters.
Category 3 hurricane is Winds (1 min sustained winds): 111-130 mph
Category F2 tornado is Significant Tornado: 112 - 157 mph
The hurricane scale goes higher - a level F3 tornado (158 - 206 mph) would be a category 5 hurricane (>155 mph) and there's no match for a F4 or F5 tornado. And thank you very much for that...
Live today, because you never know what tomorrow brings
Yeah, generally you don't even try to build to withstand a direct hit from a tornado, it'd just be way too expensive. The odds of any particular building getting smacked by a tornado are fairly small, and even a big tornado affects a much smaller area than your average landfall hurricane.
Designing to survive hurricane force winds is much more feasible, and it's cool to watch some actual experimentation. Note from the video, that right before the house on the left collapses, the front door is pushed open. Once the wind gets into the house, it needs to go somewhere, and it basically lifts the house up allowing it to fall over. You have to bolt the whole house together vertically, from the foundation all the way up to the rafters.
One time I threw a brick at a duck.
If they wanted to see what the effect of a class 3 hurricane, they should come to my house and look at my kids rooms. Some people already think I was simulating an F5 tornado.
I asked someone from Environment Canada what the difference between an F4 and F5 tornado was, his answer was "an F4 destroys everything, an F5 destroys everything and cleans up after itself". Given those parameters, it sounds like your kids are only simulating an F4. ;)
They say a little knowledge is a dangerous thing, but it's not one half so bad as a lot of ignorance. - Terry Pratchett
How much cheaper, really? Let's take the example of having modular prefabbed floors & exterior walls that are available in many configurations so you have design freedom to build what you like. These prefabbed sections can be mass produced, cheaply, and the right combination shipped to the location. Once there, you flip it up, use whatever connection method is needed for the walls and lay down the interlocking floor sections. The prefab sections I saw near Munich even had insulation built into them.
With wood, the wood has to be processed, granted at a much lower cost than the concrete section fabbing. Then it has to be shipped just like the prefabbed. But then it changes - The amount of labour that goes in to laying floor joists, laying & fastening floor sheets (which all results in a boing-ey floor anyway), framing wall sections on the floor then raising them, then ultimately installing insulation and poly, is quite a lot more than I imagine an efficient prefab production line would be.
Note that I have no actual idea of the relative costs of anythign above, but i'm genuinely curious as i'm sure that an efficient prefab system could turn out cheaper, or at least on-par. Then you get the benefit of stronger houses. Oh and there's nothing to stop you doing the internal framing with wood/metal studs, so you still get the freedom to change/customise the internal layout.
I do agree, however, that pure brick or poured concrete buildings would be more expensive. I also agree that *right now* it would be more expensive as an efficient prefab infrastucture would need to be built up over time. With the "PROFIT NOW, NOT LATER!!!" mentality of businesses over here, this is not likely to ever happen.
To clarify, the smallest hurricanes have a larger geographical footprint than the largest tornadoes. A hurricane cannot form in a small area, and a tornado cannot be that large; the difference is in intensity. Tornadoes have much faster winds. Despite this, hurricanes are a larger source of damage.
In fact, the largest losses to insurance due to tornadoes+hail+wind in a given storm is just over $2bn, which is a big yawn compared to a large hurricane loss. It wouldn't make the top 20. Average loss per year for insurers due to hurricanes in the US has been higher than that, in the last 15 years or so. (And insurers are better at not paying claims for hurricanes, since "storm surge" is excluded due to it being flood.)
I'm a concientious
Well, yeah, once something is happening, the odds of it happening are pretty high. Anyways, I'm not try to belittle tornadoes, I actually find them far more scary than a hurricane, because with a hurricane we have ample warning to get out of the way.
But for your average home in kansas or some other tornado prone state, the overall chance of that house being hit by a tornado in its lifetime are less than the odds of a house in florida to be impacted by a hurricane in its lifetime. That combined with the fact that designing to protect against hurricane force winds is a good bit easier than designing against tornado force winds has led to our society in general to decide that for most of our buildings, the costs of tornado proofing are not worth it.
Better to send the people underground or wherever is safe, and just let the tornado have its way with the buildings. Mother Nature wins that fight by default, we don't even try to step into the ring.
One time I threw a brick at a duck.