Why aren't there tornado safety building codes?

[Dave (imported)]

>>This was part of a discussion I seem to have lost.

>>

Why aren't there tornado safety building codes?

High construction cost, infrequency of severe twisters among the reasons

By Natalie Wolchover

updated 4/30/2011 3:10:39 PM ET

http://www.msnbc.msn.com/id/42836117/ns ... e-science/#

Tornadoes kill an average of 80 people annually in the Midwest and South, and in some years, many more. The twister death toll this year has already topped 300. By contrast, no one has died in an earthquake in the United States since 2003. While earthquake-proof building codes are becoming ever more stringent for structures built in the country's earthquake zones, why are there no tornado building codes in Tornado Alley?

According to Tim Reinhold, senior vice president for research and chief engineer at the Institute for Business and Home Safety (IBHS) in Tampa, Fla., it comes down to something called the "return period" — the interval between two disaster events in a given location. Although major tornadoes happen every year, the likelihood they'll happen twice in the same place is very low.

"In some areas of California, earthquakes happen tens or hundreds of years apart, and they affect a tremendous area with a lot of properties," Reinhold told Life's Little Mysteries. "But for a tornado hitting a particular location in Tornado Alley, you're dealing with return periods of thousands of years."

Earthquake building codes, Reinhold explained, vary between regions, but at their most stringent, they only apply to areas with disaster return periods of 500 to 1,000 years.

"Building codes are required for a building that, in any given year, has a 1 in 500 to 1 in 1,000 chance of getting destroyed by an earthquake," he said.

"With tornadoes, because they're relatively small and don't cover very much ground, the chances that a particular building in Tornado Alley would be hit is 1 in 5,000 per year. And within that, the chance that the tornado will be F4 or F5 [the highest levels on the Fujita scale] is even lower. So to make everyone build houses to stand up to that level would be a huge cost increase and we'd all be living in concrete bunkers," Reinhold said.

Whether we're driving, flying in an airplane, or simply living in Tornado Alley, there is always some risk involved in human activities, he pointed out.

Though neither the state nor the federal governments require it, there are precautions people can take to protect themselves in the event of a tornado.

"The best thing people can do for personal safety is to put in a storm shelter," Reinhold said. "There is money available from FEMA to help people if they want to build a storm shelter which is designed to withstand 200 mph winds and to resist a two-by-four [piece of wood] hitting the wall at 100 mph. It depends on whether the state is participating as to whether those funds are available."

If people don't want to build storm shelters, "there are guidelines available for what you can do to create a safe area in a home or business as opposed to strengthening a whole house," he said. One example is to strengthen the wood studs in the wall of an inner room.

"FEMA says when a tornado is threatening your area, the key is having a safe place to go and enough time to get there," he said. The National Oceanic and Atmospheric Administration (NOAA) broadcasts weather information all across Tornado Alley, so people should keep their radios tuned in, he said.

http://www.msnbc.msn.com/id/42836117/ns ... e-science/#

[Riverwind (imported)]

Dave you should already know the answer to that, Tornado's don't hit cities, they only hit out in the country and trailer parks.

Don't get me wrong, my heart goes out to the people that lost everything, but some of the damage was from Cat5 Tornado's which is like a 9.5 earthquake, no building code will help that.

River

[Dave (imported)]

I kind of agree with you. It is really hard to build an entire house tornado proof.

[moi621 (imported)]

Maybe not the perfect storm but better protection for lesser ones.

I liked the idea of steel net held on roofs.

Bullet proof like material would help against the flying projectiles.

Strapping structures onto the foundations.

Designated shelter areas. Like a safe room.

Door, window and shutter designs. Roof angles.

No doubt "they" could do better. and not necessarily conflict with earthquake needs.

Moi

[nullorchis (imported)]

When the wind picks up a bus and moves it at 150 mph it would take a solid wall of steel reinforced concrete to withstand the impact. Tests have been done but I don't know how thick the wall would need to be.

Living underground or in a cave are just about your only options when it comes to a tornado. If hit directly, first the 150_+ wind goes one direction then seconds later it goes the other direction as the tornado passes. You are inside a massive blender.

The best building code to avoid tornado damage is to live someplace where tornadoes don't occur. But then, most of those places are either unaffordable, or undesirable. Perfection is just hard to find.

Volcanoes, Earthquakes, tsunami's, tornadoes, hurricanes, floods, bugs, mold, among other things, make this planet one challenging place to live. Makes you wonder why our ancestors ever decided to colonize the place.

[JustAGuy (imported)]

Maybe not the perfect storm but better protection for lesser ones.

I liked the idea of steel net held on roofs.

Bullet proof like material would help against the flying projectiles.

Strapping structures onto the foundations.

Designated shelter areas. Like a safe room.

Door, window and shutter designs. Roof angles.

No doubt "they" could do better. and not necessarily conflict with earthquake needs.

Moi

Problem with the bullet proof like materials, they are made to stop blunt objects (i.e. a bullet proof vest protects against bullets but will do nothing for say something pointed like a knife)

Steel net.....may be effected against something weaker like F1 or F2 but anything stronger it would probably fail. There really isn't anything you could do for a truly strong one, as was stated in an earlier post. Unless you make something entirely out of thick tungsten or diamond I doubt there would be much you could do.

[raymar2020 (imported)]

Tornadoes are by their very nature erratic and unpredictable. To attempt to build to protect against them is nearly impossible. The shear force of the winds in and F5 storm is such that nothing is safe.

As a guy who spent many years in the construction business both in and out of tornado alley, I can assure you that most local codes call for strapping and bolting a structure to the foundation. There are also now requirements that joist hangers be used in roof construction, as well as walls. These things will help a structure to survive a relatively minor storm, or even withstand the winds associated with a larger storm. Debris however can not be taken into consideration when building. The real killer for many structures in a tornado is the debris from other structures that we destroyed being flung at it with great force.

The best defense for tornados is to have a safe UNDERGROUND space to escape to , and to always be mindful of the weather. In the recent storms some places that actually have tornado warning systems , never had the chance to use them.

Nature is a cruel thing, and cares not what man has built, so we must act to provide as much protection as possible in areas that are vulnerable to such storms.

One other thing, the issue with storm shutters , and other methods of protection is not sensible with tornados. The warning time is so short that there is little chance that they could be closed to offer protection. Hurricanes give ample warning to close up before they strike, but a tornado can form in minutes, and moves very very fast.

Raymar

[Kortpeel (imported)]

Dave you should already know the answer to that, Tornado's don't hit cities, they only hit out in the country and trailer parks.

Don't get me wrong, my heart goes out to the people that lost everything, but some of the damage was from Cat5 Tornado's which is like a 9.5 earthquake, no building code will help that.

River

Two questions:

1. If that is literally true, how come tornadoes don't hit cities? Are there no cities in tornado alley?

2. What parts of the US have both tornadoes and earthquakes?

Please note, I'm not making a point here. Just requesting information.

[kristoff]

Two questions:

1. If that is literally true, how come tornadoes don't hit cities? Are there no cities in tornado alley?

2. What parts of the US have both tornadoes and earthquakes?

Please note, I'm not making a point here. Just requesting information.

He was being facetious. Of course, tornadoes hit cities, as well as trailer parks.

[Riverwind (imported)]

Volcanoes, Earthquakes, tsunami's, tornadoes, hurricanes, floods, bugs, mold, among other things, make this planet one challenging place to live. Makes you wonder why our ancestors ever decided to colonize the place.

They had to put the penal colony somewhere, Earth looked like a nice spot.

River