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Tornados and Wind Zones

jar546 said:
I think this is about reducing risk and protecting people whether in their own home or out and about in public places.If there are 200 people shopping in a Walmart, is there a room big enough to fit all of them?

I would think (unscientific opinion) that having buildings in areas prone to tornados (of different categories) built to a higher standard just like those on the coast would increase the likelihood of survivability. All wood structures just don't cut it.
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Walmarts seem to be tornado magnets--a few examples

Colonial Heights VA a number of people killed and injured when a tornado struck a Walmart

Killer Tornado Devastates Old Petersburg in Virginia - NYTimes.com

Nonfatal hit in Joplin MO

At Joplin Walmart, Death, Survival and the ‘Best Soda I Ever Had’ - Dispatch - WSJ

Minor hit Athens AL

Athens, Alabama: Tornado Possibly Hits Near City, Knocking Down Trees And Flipping Dumpsters

6 injured Mobile AL

High winds tear Wal-Mart roof, 6 injured | al.com

Branson

http://www.newson6.com/story/17043166/one-killed-13-injured-by-possible-southwest-missouri-tornado

That said The smaller tornados do significant damage but largly do not result in structural collapse, however the larger ones are catastrophic. It becomes a question of probability vs cost--Building homes, big boxe retailers schools etc. with heavy conctrete construction--about the only real protection from a catastrophic tornado is somewhat cost prohibitive. With some buildings like schools incorporating shelter construction in a central hall is achievable--how you do it for the 2500-3000 occupants of a big box retailer is more challenging while maintaining the open floor plan.

As mentioned below these are low probability but high impact events.

A more common death/injury/damage event not addressed by code are vehicle impacts including the very common car into the convenience store/apartments/house etc up to less frequent aircraft and spacecraft impacts. In our jurisdiction we condem more buildings for these than for fires or wind events that are addressed by code.
 
This may have already been posted but given that Moore Oklahoma was hit in 1999, 2003, and 2013; and then we had 5 tornados waltz across Oklahoma County (From El Reno to Mid-west City) Friday night (5/31/2013); I think something should be done for areas that are tornado prone as far as building design requirements. As stated before we are in 90 mph or less wind speed requirements. It may not keep an EF 4 or 5 from destroying your home; but we have many high winds and damaging tornados in our area. I would like to see special requirements for special areas like our Tornado Alley. Even in the EF 5 that hit some people were saved by being in a small room in the interior of the house. If we were required to build to a higher standard than I-codes require, I believe more people would be saved. A safe room or storm shelter runs from about 5 to 8 thousand dollars and most cannot afford it; but, if higher standards were required then at least more people would have a chance at surviving. I can't make a new paragraph but hope this link works NCDC: Educational Topics: Enhanced Fujita Scale . We can save more lives. Our local TV and radio stations have saved hundreds of lives thru their early warning system; probably the best in the country. Friday evening El Reno had a 19 minute advanced warning, which is very good compared to what we had in 1999. People who didn't have storm shelters were told to get below ground or get out of the area immediately. I 240 and I40 were jam packed with cars and the results of a tornado going down those hwys would have killed hundreds. If they just had better structures perhaps they could have gotten into a middle room and been much safer. Also, on a more regular basis we have hail in many of our storms and hail damage is always a problem here. Hail that is from ping pong ball to tennis ball size is not unusual here. That is not taken into account when constructing homes. I know you can't regulate guaranteed safety; but more stringent regulations in this area should be a no brainer. On the EF scale in the link; those "3 second gusts" are continuous within our tornados that can be from a few hundred yards to a mile wide. Couldn't some of you Engineers design a retrofit room in existing homes that would be more safe than getting in your car a trying to dodge tornados dancing through the area? Uncle Bob
 
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Ok, ya'll, I'm on a quest. FEMA has plans that may have a reasonable cost for folks to build an all wood, above ground in your home storm shelter; and there may be grant money available to help. What I'm trying to do is download the "Residential on slab wood storm shelter" plans (the one without steel sheet on interior please); but FEMA requires some kind of auto-cad crap for me to do it and when I click on the help line they provide my computer says NO don't do it; can't be trusted. I figure if I can get the plans, I can submit a material take-off list to my local lumber companies (who have been co-operating with me and been helpful on other projects); and find out what it will cost for this type FEMA "approved" all wood storm shelter. If I can get this project together, we might be able to get storm shelters in "existing" homes here at a fairly low cost; or with FEMA grant money "very low cost". :) Here is the website; FEMA P-320 - Taking Shelter From the Storm: Building a Safe Room For Your Home or Small Business | FEMA.gov If anyone can download and post or give a link to this plan for the all wood above ground in home storm shelter; I will be very greatful. Now I can't get rid of the stupid line or bold print. Ok I got rid of that. Any assistance will be appreciated. Uncle Bob
 
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Thanks Fellas the link word Phil. Now all I have to do is figure it out and do a material take-off to see what it will cost. I'm hoping that materials will be less than $1000; and now I can look into the FEMA grants and see how they will benefit the homeowners.

Again, thanks,

Uncle Bob
 
Uncle Bob said:
Thanks Fellas the link word Phil. Now all I have to do is figure it out and do a material take-off to see what it will cost. I'm hoping that materials will be less than $1000; and now I can look into the FEMA grants and see how they will benefit the homeowners.Again, thanks,

Uncle Bob
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A takeoff list is provided in the last couple of pages.
 
This posting will soon appear on my daily blog (with better formatting):

On the afternoon of May 20, 2013, an EF5 tornado, with peak winds estimated at 210 miles per hour (mph), struck Moore, Oklahoma, and adjacent areas, killing 23 and injuring 377 others. The tornado was part of a larger weather system which had produced several other tornadoes over the previous two days. The tornado touched down west of Newcastle, OK staying on the ground for 39 minutes over a 17-mile path, crossing through a heavily populated section of Moore. The tornado was 1.3 miles wide at its peak. Despite the tornado following a roughly similar track to the even deadlier 1999 Bridge Creek-Moore tornado, very few homes and neither of the stricken schools had purpose-built storm shelters

Between 12,000 and 13,000 homes were destroyed or damaged, and 33,000 people were affected. Most areas in the path of the storm suffered catastrophic damage. Entire subdivisions were obliterated, and houses were flattened in a large swath of the city. The majority of a neighborhood just west of the Moore Medical Center was destroyed. Witnesses said the tornado more closely resembled "a giant black wall of destruction" than a typical twister.

The Oklahoma Department of Insurance said the insurance claims for damage would likely be more than $1 billion. Total damage costs have been estimated as high as $2 billion.

How did all of this happen?

Home builders protest the estimated cost of $2,000 to $6,000 for home tornado shelters would make houses unaffordable. How much is a human life worth? If it is one of my loved ones, a whole bunch more than this.

Some of the fault might be placed upon local government, as well as the Building Departments which provide recommendations for design wind loads for structures. The design wind speed for the Moore area, by Code? 90 mph or roughly 20.736 psf (pounds per square foot). Consider 210 mph is over 107 psf – more than FIVE TIMES the design wind load!!

Anyone wonder why the photos were as astonishing as they were?

Not trying to be confusing….the values we use for wood design are based upon 40% of a 5th percentile figure. As an example, if 100 random pieces of lumber were tested for strength, and the values plotted on a curve, take the 5th lowest value from the bottom, and use 40% of this value. This does afford a certain amount of cushion in wood design.

At the least, I’d recommend increasing the required design wind speed to something in the range of 150 mph (57.6 psf) to 170 mph (74 psf). While this would not eliminate all destruction, it would certainly tend to be better than what exists currently.

In examining a fairly significantly sized full enclosed pole building kit package (40 feet wide by 60 feet long and 14 foot tall), the price increase from 90 to 150 mph design wind speeds was just over 10% (not much more than $1200).

Post frame construction lends itself naturally to being resistant to extreme wind loads. With columns embedded in concrete backfill, there is no weak point at ground level, as found in conventional stick frame construction, or manufactured housing.

With a minimal number of mechanical (nails, etc.) connections, as compared to stud wall buildings, pole buildings run a far lower risk of compromising these crucial joints.

Play it safe – play it in a post frame building designed to actually support the types of loads which it could be hit with.
 
Polebarnguru, welcome to the forum. You stated "Play it safe – play it in a post frame building designed to actually support the types of loads which it could be hit with". However, all "pole barns" in my jurisdiction are required to be engineered; because they do not meet code requirements; and are NOT allowed to be used as a residence. We have several people who try to turn "pole barns" into homes here and are not successful. Their reasoning is understandable; because you can get a 20' X 30' pole barn built for about $12,000 (outside of town). I totally agree with increasing the wind speed requirements; and there isn't a pole barn in Oklahoma that can meet the requirements we have now even for a barn/shed without engineered design. Hope your pole barn business and blog are successful. Uncle Bob
 
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Block CMU construction as we see in high wind areas such as Florida are even better than pole barns. We have way too many problems with uplift during high winds with the pole barns and I have been involved in civil cases against pole barn contractors. There is no way that a pole barn can compete with masonry construction with vertical and horizontal rebar and bond beams. I am hoping that PoleBarnGuru continues to participate because at this point I am highly suspect of his self serving motives with a single post.
 
A couple of buckets full of framing clips, brackets and such would cost about the same as coffee & donuts consumed building new housing.
 
mtlogcabin said:
Insight: In tornado alley, building practices ***** damage
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Excellent article. I am happy to see this much attention being brought to the masses. On a side note, the governor does not sound to intelligent.
 
From Mountain Man's Link:

The last five years have seen the highest losses from thunderstorm damage in U.S. history, according to an analysis by insurer Munich RE.and:

Damage costs are rising because of increased population density, even in mostly rural states such as Oklahoma, which has seen substantial urban sprawl in the last decade, said Greg Carbin, Warning Coordination Meteorologist for the National Weather Service's Storm Prediction Center in Norman, Oklahoma.
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With an exploding world-wide population this is only going to get worse as large areas of the population are relocated to the less expensive heartland and southern areas of the country. Mac's "A couple of buckets full of framing clips, brackets and such would cost about the same as coffee & donuts consumed building new housing." will only be a start, like everything else this will expand to the way we are having to build, those "couple of buckets of framing clips" will soon lead to steel moment frames and full red iron frames like I am now doing, add to those costs the costs of the Energy and Green codes and we are at a minimum of $500 a foot for code minimum structures to $1,000 a foot and more for quality construction, I budgeted $100,000 for Special Inspections and will make it. A former carpenter of mine fully documents the projects he works on as a framing contractor, take a hard look at what we are doing:

A 5,600 square foot new home.

A 7,000 square foot remodel and addition.
 
conarb said:
From Mountain Man's Link:With an exploding world-wide population this is only going to get worse as large areas of the population are relocated to the less expensive heartland and southern areas of the country. Mac's "A couple of buckets full of framing clips, brackets and such would cost about the same as coffee & donuts consumed building new housing." will only be a start, like everything else this will expand to the way we are having to build, those "couple of buckets of framing clips" will soon lead to steel moment frames and full red iron frames like I am now doing, add to those costs the costs of the Energy and Green codes and we are at a minimum of $500 a foot for code minimum structures to $1,000 a foot and more for quality construction, I budgeted $100,000 for Special Inspections and will make it. A former carpenter of mine fully documents the projects he works on as a framing contractor, take a hard look at what we are doing:

A 5,600 square foot new home.

A 7,000 square foot remodel and addition.
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I think I saw a missing rebar in the foundation for the Woodside project. I think there is more weight in steel than concrete in that foundation! LOL
 
Everthing should have a cost benefit analysis, the home I am trying to finish up now at $1,000 a square foot, field inspection has been minimum, on my first inspection request the field inspector told me the home was too complex for him at 125 pages of plans including shop drawings, I should go through a designated SE in plan check. View attachment 1674In the 50s and 60s I built many homes and apartments with stick framing not much better than the homes shown in the Oklahoma disaster (all did have foundation bolts, but at first the then code minimum ½"x10" foundation bolts), my only structural failures have been lightweight roof trusses where the gang-nail plates pulled out at about 25 years.BTW, every AHJ handles enforcement differently where I am building by making it a remodel I got through the application process in two years, of which one year was fights between my SE and the plan check SE, in the Woodside home it breezed through plan check but then the field inspector put them through 7 straight days of framing inspection, finally the carpenter asked me to show up and argue code with the inspector, as he walked through he repeatedly asked to have nails pulled so he could measure and mic them, I've never seen that before. As to Mac's "couple of buckets full of framing clips" the Woodside home has $30,000 worth of Simpson products, another $30,000 worth of red iron, and I'd estimate that the installation costs of the Simpson installations to be around $60,000, that was the point that I decided no more stick framing, it's cheaper and better to go all steel frame with the added advantages of walls of windows and not having to seal up walls allowing them to breathe, the only diaphragm sheathing I have is interior walls, and that optional to take the flex out of the steel frame.

View attachment 721

View attachment 721

/monthly_2013_03/2342.jpg.1fd2bbe52dd280ecfc96251bdb44b19b.jpg
 
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The city of Moore, Oklahoma allows nails shot with nail guns (no specification requirements for type of nails) for foundation anchorage. Anchor bolts are not required. Also the Oklahoma Uniform Building Code Commission adopted an amendment to 2009 IRC, R403.1.6 that required anchor bolts; allowing shot nails instead. "748:20-5-7. IRC 2009 Chapter 4 Foundations

Chapter 4 is adopted with modifications as follows:

(2) Section R403.1.6 Foundation anchorage. This section has been modified to include the following exception: Wood sole plates of braced wall panels at building interiors on monolithic slabs may be anchored using connector(s) with a shear capacity of 2300 pounds and a tensile capacity of 800 pounds over a maximum span of 6 feet." They totally ignore "and all wood sill plates shall be anchored to the foundation with anchor bolts, etc." Of, course the fact that they haven't a clue about codes and are appointed by the Governor does have some effect on their decisions. The anchor bolts would not have made a significant difference in a tornado but the fact that after the 1999 tornado building codes were weakened should be evidence that they just don't give a good crap. The Building Official in Moore is in name only; and has zero experience and knowledge of building codes. I had a discussion about a code question with the then only building inspector back in 2011 concerning single family residences and he insisted that he could show me where I was wrong. In his office he started looking for the answer to the code question in the IPC, IFGC and IMC; when I noticed the 2009 IRC still in it's wrapper, opened it and showed him where the answer was. He said "Oh, that we don't use the IRC". Enough said I guess. If ignorance is bliss, Moore, Oklahoma is a wonderful place to live. Here is the amendments to the OUBCC 2009 IRC as adopted by the state of Oklahoma; http://ok.gov/oubcc/documents/Permmanent%20Rules%20-%20IRC%202009.pdf Uncle Bob

 
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Uncle Bob said:
..... Also the Oklahoma Uniform Building Code Commission adopted an amendment to 2009 IRC, R403.1.6 that required anchor bolts; allowing shot nails instead. "748:20-5-7. IRC 2009 Chapter 4 Foundations
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Cut off all federal funds for rebuilding....
 
We can reduce the damage of building by increasing the education about building codes. We need to build the tornado proof structures to avoid the damages.
 
mark handler said:
Cut off all federal funds for rebuilding....
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Mark, I agree 100%. Until big brother starts denying federal funds where codes are not adopted and enforced this nightmare will continue. Uncle Bob
 
mark handler said:
Cut off all federal funds for rebuilding....
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Isn't there a bill or maybe it passed to increase federal dollars to jurisdictions that adopt the latest codes? Then again the latest codes are still only 90 MPH wind zones for that area.
 
The AHJs could adopt the ICC-600 taking the 90 MPH to 250 MPH, as far as storm rooms there is a code for that too:

Simpson said:
The ICC/NSSA Standard for the Design and Construction of Storm Shelters, ICC-500-2008, is the national standard. The ICC-500 contains requirements for design and construction of both tornado and hurricane shelters (depending on your geographical location), and residential and community shelters (depending on the number of people for which your shelter is planned). You can buy the ICC-500 here.Storm shelters designed to ICC-500 have to be able to resist extremely high wind speeds; the highest expected for that part of the country. For much of Tornado Alley, that’s 250 mph (see windspeed map below).In less hazardous areas, generally west of the Rocky Mountains, wind speed falls to a low of 130 mph. The walls, roofs, doors and structural connections, including the connection to the foundation, all have to be designed to resist wind loads calculated from these wind speeds using special equations and load combinations in the standard.¹
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¹ Building a Storm Shelter to ICC-500 Design Requirements | Structural Engineering Blog
 
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