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Building in the lands of tornadoes

 
 
Reply Sun 29 May, 2011 02:33 pm
I know a bit about pros and cons re building in earthquake prone areas, but nothing much at all about building where tornados are apt to occur. I think I know that people build safety cellars if they can - but that's all I know. Are there building codes that address the issue? I can imagine, given the trouble to the hospital in Joplin, that even a presumably study structure can't withstand - what was that, 200 mph force?

I'm wondering if there are houses bolted to concrete piers with steel connectors, and roofs tied to walls with steel, and perhaps corners secured with steel angles.. or would even concrete piers be pulled up with a direct tornado hit....
or maybe such efforts could help at least the outliers to the zone of destruction.
or is that just fantasy?

I can google this and probably will, but am naturally inclined to ask here on a2k first.

I'm also not just thinking of the US as tornados occur in other places too, though wiki says the vast majority occur in the tornado alley of the US.
(http://en.wikipedia.org/wiki/Tornado)
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Type: Discussion • Score: 7 • Views: 2,122 • Replies: 15
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ossobuco
 
  1  
Reply Sun 29 May, 2011 04:01 pm
@ossobuco,
An article at MSNBC on why there are no tornado safety building codes:

http://www.msnbc.msn.com/id/43142883/ns/technology_and_science-science/t/why-are-there-no-tornado-safety-building-codes/
0 Replies
 
realjohnboy
 
  1  
Reply Sun 29 May, 2011 04:24 pm
My understanding, Osso, is that there is no "traditional" building technique (ie bricks, block, lumber) that would ever make a structure tornado proof. You would need to look at steel and concrete (and eliminating windows) for anything above ground.
A story on NPR involved a family who buried an old school bus in their back yard, with only the rear door accessible. It served them well, even though their house was lost.
ossobuco
 
  1  
Reply Sun 29 May, 2011 05:31 pm
@realjohnboy,
Well, what about concrete block with the cells filled with steel and concrete, set on a concrete foundation? My brother in law - the building inspector - bought a house like that in California. It did have windows, even a couple of picture windows, but fairly spare ones compared to some other houses. I can't right now visualize the roof he put on (he added a second story), but I'm sure it was somehow steel connected knowing him. Admittedly I find the house rather cold in nature. Oddly, I also remember my father talking about concrete block houses, and that would have been back in the early sixties.
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realjohnboy
 
  1  
Reply Sun 29 May, 2011 05:54 pm
I am way over my head on this, Osso.
Tornado proofing and earthquake proofing are two different things. My understanding is that, in the case of tornadoes, the construction costs and the architectural details (ie windows) are daunting. The odds of a house getting hit argue for building a standard house, with a below ground shelter for personal protection reached after increasingly more timely warnings.
But I can't vouch for any of that.
ossobuco
 
  1  
Reply Sun 29 May, 2011 06:42 pm
@realjohnboy,
That makes sense. I do know and know you know I know (heh) that earthquake proofing and tornado proofing are different. I was just wondering what is tornado proofing - or if not proofing, strengthening, if any, besides the below ground shelter. I don't even know, having not checked it out before, if some buildings in the path make it and others don't.

Or - do structural engineers in the area do anything different for their own houses, or houses they are consulting on the design of?
ossobuco
 
  1  
Reply Mon 30 May, 2011 07:07 am
@ossobuco,
I would guess that shear stress has a lot to do with the way a tornado pulls a house apart - and on that guess, I wonder if there are building codes rules in place that are any different from universal building code points (not that I've looked those up lately).
Eva
 
  1  
Reply Mon 30 May, 2011 06:39 pm
@ossobuco,
Local builders often recommend "safe rooms" in new house construction here. You can google that and find lots of information. Costs about $5,000 from what I've heard...sometimes more. I know a couple of people who had them built into their new homes.

Older houses here often have partial basements. Ours does. They were originally built in the '20s and '30s for coal storage and the old coal-burning furnaces. They make great storm shelters.
ossobuco
 
  1  
Reply Mon 30 May, 2011 07:44 pm
@Eva,
I get having a safe room, and get having a partial basement. I was trying to figure out how to save the rest of the house with medium or high force twisters. I looked up recent ones in Bernalillo County (here) and the F = 0, low. The pictures from the bad ones look so devastating, maybe it's simple, there is no saving most of a house with a high force tornado.

I'll have to google safe rooms, like you say, and see what the components are. Busy the next few days but still interested.
Finn dAbuzz
 
  2  
Reply Mon 30 May, 2011 09:25 pm
Construction techniques can, entirely, protect a home from winds up to about 110 mph that would utterly destroy the lesser contructed homes.

This is a proven fact.

Florida which annually faces the peril of Hurricans leads the country in building code mitigation. Missouri, which very recently experienced a tornadic devestation, doesn't have such building codes, but my bet is that they shortly will.

To build a home that can withstand 110mph winds costs about $3,000 more than building one that will be a pile of match sticks in the face of a H2 storm.

Now, I fully expect A2K libs to blame the builders of these homes, but what you fail to appreciate is that these capitilist swine have to sell their product to someone, and most of their potential customers care more about price than damage mitigation.

The State needs to intercede only because it has previously, for purely politically reasons, interceded in home buying.

Allow the market to run free and we would have have people building stout houses and the ones who don't not doing so...but once.





hamburgboy
 
  1  
Reply Mon 30 May, 2011 09:32 pm
@ossobuco,
osso :

adobe built houses are being offered as being both tornado AND hurricane proof ... of course there is always the question of cost , isn't there ?
hbg

see article :

http://www.adobemachine.com/tornadoproof.htm
ossobuco
 
  2  
Reply Tue 31 May, 2011 07:54 am
@Finn dAbuzz,
You have this tendency to paint all libs with the same brush, Finn.
I understand government interest in safety codes - at the same time I've a view towards living lightly on the land and thus get having a quite minimal cabin, cottage, etc.
I am interested in ways to help strengthen a home, and I'm aware that they can be strengthened re some forces. California seismic building codes, for example, have changed over the years as more is learned. Earthquakes vary in type and tornadoes and hurricanes obviously vary from earthquakes with their forces, but some of the structural aspects for allaying the force problems might be similar. Or differ. Thus my question.
0 Replies
 
ossobuco
 
  1  
Reply Tue 31 May, 2011 07:55 am
@hamburgboy,
I'll have to look at that, hamburgboy.
ossobuco
 
  1  
Reply Tue 31 May, 2011 08:18 am
@ossobuco,
Finn, on builders, I can see both sides of that. I'd consider builders individually. The scoundrel who developed my housing tract borders the scum are, not for what you say, but for extremely sloppy construction. I designed for a few developers for some years and have some clues about good work.
0 Replies
 
joefromchicago
 
  2  
Reply Tue 31 May, 2011 08:44 am
@Finn dAbuzz,
Finn dAbuzz wrote:

Construction techniques can, entirely, protect a home from winds up to about 110 mph that would utterly destroy the lesser contructed homes.

This is a proven fact.

A tornado with wind speeds of 110 mph would be considered at the top end of "moderate" on the Fujita scale (F1). F1 tornadoes rarely do much damage anyway, regardless of the type of home construction -- unless we're talking about mobile homes. Hurricanes with wind speed of 110 mph will do more damage than a tornado with the same wind speed because they're bigger storms with attendant storm surges, not because normal houses can't withstand 110 mph winds.

Finn dAbuzz wrote:
Florida which annually faces the peril of Hurricans leads the country in building code mitigation. Missouri, which very recently experienced a tornadic devestation, doesn't have such building codes, but my bet is that they shortly will.

I'd take that bet.

Finn dAbuzz wrote:
To build a home that can withstand 110mph winds costs about $3,000 more than building one that will be a pile of match sticks in the face of a H2 storm.

Again, most homes in the midwest could easily withstand an F1 tornado without any additional structural enhancements. The tornado that hit Joplin, in contrast, was probably an F4, with wind speeds around 200 mph. Hurricanes never develop wind speeds that high. To build a house that could withstand the worst tornado (wind speeds in excess of 250 mph), one would have to build a structure that pretty much duplicated all of the attributes of a storm shelter, which kinda' defeats the whole purpose. I seriously doubt that anyone in Missouri or elsewhere in the tornado belt would contemplate building codes that are that stringent.

Finn dAbuzz wrote:
The State needs to intercede only because it has previously, for purely politically reasons, interceded in home buying.

Really? You're advocating state intervention?
deepat
 
  1  
Reply Mon 29 Aug, 2011 03:19 am
@joefromchicago,
Thanks
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