On 5/22/2013 9:56 AM, bud-- wrote:
...
> I am surprised schools do not have a safe shelter. Probably will be a
> lot more common in the future. They could also be a community shelter. A
> school at least half-way north in MN was recently destroyed by a strong
> tornado. The rebuilt school has a FEMA rated shelter.
...
They do now; drove thru OKC yesterday on way back home from TN and
listened to much local radio coverage on way thru...they said that
particular school was built in 70s and was typical of the time which
would be just light industrial-type construction of block walls w/
welded roof trusses.
>> They would need an actual shelter. I understand that there is no
>> construction that could hold up to a 200 mph wind.
>
> You can build to protect from any wind speed you want. FEMA has provided
> subsidies for shelter rooms good for 250 mph wind. A lot of shelter
> rooms have been built. Some people whose houses were destroyed rode out
> the tornado in shelter rooms. Some included neighbors. That must be one
> reason the death toll was so low.
TA&M has done a bunch of work on safe room construction and has quite a
bit of online footage of test projectile shots, etc., ... We did some
support work at ORNL for the defense facilities at the DOE plants in Oak
Ridge while there to protect nuclear processing facilities there. Many
of the production buildings there are still from Manhattan project days
or the Cold War buildup in the 50s and were, of course, built either as
"temporary" structures in the beginning or to simply meet the present
need in the 50s. So, 60-70 yr later they're still hollow clay tile
infill walls between columns on as much as 20-ft spacing and 20 to 60 ft
tall. Needless to say, they wouldn't take much--fortunately likelihood
of large tornadoes there is very low altho there were several small ones
within a couple of miles of the facilities during our 25 years there so
like almost everywhere in the US they're not unknown...
Anyway, as noted elsewhere it's possible to do quite a lot w/ only a
relatively small amount of effort--it's just that a tuabafor wall w/
some sheathing and a layer of sheetrock is essentially invisible to a
missile approaching at 100+ mph w/ a small cross section in the forward
direction (another tubafor, iow).
>> I'd probably get in
>> my basement and stand under house's steel beam.
>
> Low down in a corner would likely be safer. NWS recommends under
> workbenches. There are few, if any, basements in Moore. Reports said
> only 31% of US houses have basements. If there is no basement, shelter
> rooms can be built on the first floor and aren't that expensive for a
> new house. Small rooms underground are also built.
...
In the basement, that's probably better agreed, altho against the
approaching-direction wall under a solid beam would be pretty good _if_
the beam support is secure. If it's on a block wall that's above grade
maybe "not so much". One of the big problems in conventional basements
for storm cellars is they're not designed for egress in the aftermath.
Don't know about Moore, specifically, how it was generally developed.
If much of it was tract housing wouldn't be surprising as they were
generally built as slab for low initial cost. In local town in SW KS
generally homes are and have been built w/ basements precisely for that
reason since very early on--the farmhouse we're in was built by g-father
and started in 1915 within the year after homesteaded the home place and
they lived in the basement after it was roofed over while finishing the
rest. Some tract houses built in the late 50s thru early 70s in town
were built on slabs, however, owing to them being built during the early
gas expansion phase when quick 'n cheap was more important than other
considerations.
Generally, in conventional housing basements are better if below grade
and not just half-depth so still can collapse a block wall, say on top
of you. In an EF5 like Moore, above ground w/ conventional construction
there's a pretty good chance it'll just level it to the main floor.
That's what happened in Greensburg, KS, a few years ago, and what
appeared in what footage I've seen to be the case in quite a few cases
in Moore.
There are a fair number of just storm cellars on some of those. All the
schools have been at least modified to have solid walls added as infill
where were initially just block walls and roofs over those areas also
strengthened.
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