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Toronados

C

cda

SAWHORSE
Joined
Oct 19, 2009
Messages
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Does the ibc have requirements to design for toronados like areas prone to earthquakes????
 
The only place I found that mentions tornados is Section 423 for storm shelters. There are hurricane prone areas addressed in the code, which are based on prolonged winds and gusts. I suspect tornados are more difficult to assess what the wind speed and actual forces may be on buildings. So I think the best advise from the code is to find shelter.

There may be some local amendments to states in tornado alley.
 
The issues with designing for tornadoes are:

1. Most devastation occurs from F4 and F5 and the loads are so extreme that it quickly becomes cost prohibitive to design for such events (energy goes up as the square of wind speed).

2. Tornadoes are very limited in geographic scope and very infrequent - the odds of a building being hit by a tornado are extremely low when compared to the odds of a seismic event or hurricane in regions prone to them - which makes the economics even more questionable.
 
Would suggest that the damage due to tornados would be a lot less if the building was tied together. Look what is required in Florida and other hurricane regions.

The problem is that many owners are penny wise and pound foolish. Also many building designers and contractors do not want to admit that maybe they haven't been doing it right in the past.
 
Aside from the occasional safe room, practically nothing seems to be done to consider tornadic winds in new designs. SOMETHING would be better than nothing-- maybe those acres of lovely glass on your bldg aren't such a great idea... oh well.
 
The IBC currently does not have requirements for when a tornado safe room is required. They have design criteria if one is provided or required by local amendment. Some cities and states have adopted shelter requirements for certain occupancies.
 
Mark K said:
Would suggest that the damage due to tornados would be a lot less if the building was tied together. Look what is required in Florida and other hurricane regions.The problem is that many owners are penny wise and pound foolish. Also many building designers and contractors do not want to admit that maybe they haven't been doing it right in the past.
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Most tornadoes can be handled by a structure designed to withstand hurricanes because the wind speeds are of similar magnitudes. However, designing to withstand hurricanes adds significant costs to the construction of an SFR.

Designing for the most destructive tornadoes is cost prohibitive - and those are the ones which make the news.
 
I'm not sure what a building would look like that was designed to resist 300-400 mph tornado forces. Maybe 30 inch concrete walls with no windows?
 
cda said:
Does the ibc have requirements to design for toronados like areas prone to earthquakes????
Click to expand...
This link doesn't specifically address your question, but offers general guidance, and alternatives to more cost-prohibitive design strategies by using safe-rooms and areas of refuge.
 
High Desert,

No windows?

They call it a fruit cellar, and it works fine! Don't let the codes screw it up!

pc1
 
mmmarvel said:
Oldsmobile, had front wheel drive, heck of a ride in it's time.
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drove a 1970 model from san fran to ensenada mexico in 1970 in about 7 hours, shooting blue flames at times out the muffler. average speed about 100 mph. it was the middle of the night. amazing how some of us survived the wonder years! nice ride:mrgreen:
 
I was told to order the 2012 International Green Fruit Celler Construction Code by the boss! "Lots of pictures!" you should get yours before there all gone!

2012IGFCCC

pc1
 
Probably was the 350, all they did was refit the olds rocket gas motor as a diesel, ran great early on, not good in the long run. I had a Chevy truck with one........nice thing was, when the diesel finally puked, just go out and find the rocket 350, bolt-in installation. Got one out of a low mileage 442, now that was a nice motor! OK, a bit OT again..........sorry.
 
Look at the frequency though, the F4 and 5's make the nat'l news but the little ones are far more frequent and do the bulk of the damage. They are survivable and not that hard to build for, the same construction would save many of the structures around the big ones. Not that I'm advocating more codes, education would be my choice. We tend to say that all tornados are unsurvivable and in fact most could be built against. There were 6 not too far away recently, only one exceeded 135 mph. All did significant damage. Less than 10% of tornados are F3 or greater while approximately 70% carry winds below 112 mph.
 
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