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Re: Bomb Shelter

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Hi, Forrest and Syed:
There is still another approach described at
http://www.ecs.csun.edu/~shustov/Topic3A.htm. It may help in some cases.
Valentin.
________________

Forrest Braun wrote:

> Syed
>
> Assuming the doors are mounted on the exterior of the wall of the space
> being protected and either swing out or sideways parallel to the face of
> the wall then the wall thickness could be increased in the area of the
> door as required to accommodate the door hardware, confinement
> reinforcing for embedments in the concrete and dowels to tie these all
> into the existing wall.  The bottom line is increasing the wall
> thickness.  This could be a problem if space is limited as a result of
> facilities or planned usage on that side of the wall.
>
> syed faiz ahmad wrote:
> >
> > Forrest
> > Your point is noted. But could you please elaborate more on this "CONCRETE
> > FLANGE" that you are proposing? Thank you once again.
> > SYED FAIZ AHMAD
> >
> > >From: Forrest Braun <fbraun(--nospam--at)bbfm.com>
> > >Reply-To: seaint(--nospam--at)seaint.org
> > >To: seaint(--nospam--at)seaint.org
> > >Subject: Re: Bomb Shelter
> > >Date: Fri, 01 Jun 2001 16:09:34 -0800
> > >
> > >Syed
> > >
> > >Using epoxy concrete may not be the best solution for what are probably
> > >heavy doors since the epoxy could have significant creep, and your
> > >anchors will be in tension. Heat may also be a concern although from a
> > >blast that time period will be short.  Any resulting fire in the
> > >aftermath though could be long enough to affect the epoxy.  A high
> > >strength cement or concrete grout would be a better solution especially
> > >if the existing reinforcing can be exposed to allow the new grout to
> > >completely surround the bars.
> > >
> > >Try to avoid cutting any of the existing bars.  It will probably be
> > >necessary to cut a few to fit the hardware.  Any bars that need to be
> > >cut should be re-established if at all possible since this will be a
> > >high stress point.  Mechanical bar splicers, or welding (if weldable
> > >bars or appropriate precautions taken) I should think would be better
> > >than lap splices.  All of these take up space or may require additional
> > >demolition of concrete so you will need to look at these options
> > >carefully.
> > >
> > >An alternate to potentially affecting the integrity of the existing
> > >concrete may be to add a concrete "flange" of appropriate depth and
> > >width to the blast side of the wall to accept the door hardware.  This
> > >flange could then be doweled into the existing concrete thus providing
> > >greater flexibility in maintaining the existing bars.  Just a thought
> > >though.
> > >
> > >syed faiz ahmad wrote:
> > > >
> > > > Gentlemen/Women
> > > > I have a problem which i want to share discussions with our fellow
> > >learned
> > > > engineers on the List.
> > > > We built an underground bomb shelter which have wall openings
> > >provisioned
> > > > for the Blast resistant doors. There were no provisions left for "hold
> > > > fasts" for fixing the blast doors at the time of casting of this bomb
> > > > shelter. The peripheral walls of the shelter are 700 mm (2 ft-4 in)
> > >thick &
> > > > the intermediate walls receiving these doors are 300 mm (12-in)
> > >thick.The
> > > > top & bottom slabs are 700 mm (2ft-4in)thick. These doors are basically
> > > > leading to escape shafts & also serving some rooms. The blast doors have
> > >now
> > > > been received so we know now exactly the number & location of the "hold
> > > > fasts"; this information was not available at the time of concreting,
> > >that
> > > > is why no provisions could be made for "hold fasts" then. We are now
> > > > intending to break open portions in the walls to fix these hold fasts &
> > >fill
> > > > back the openings with epoxy concrete.These are bomb shelter walls so
> > >there
> > > > are of course, a jumble of rebars. This will involve cutting of some of
> > >the
> > > > rebars as well.There is no way to do some analysis because these are
> > >bomb
> > > > shelters designed by some Consultant some 15-20 yers ago and are being
> > > > copied generation to generation. No data on these blast forces are
> > >available
> > > > which would basically be generated by surrounding air after enemy air
> > > > attack. So,as you see, we have to work empirically on pure engineering
> > > > judgements.I know from research, structural elements repaired with epoxy
> > > > concrete become very strong & under load tests it yields from some other
> > > > locations & not at the locations where it was repaired using epoxy
> > >concrete.
> > > > This is satisfying to me & i can try & sell this to the supervising
> > > > Consultant. But there could be questions on its integrity to resist
> > >blast
> > > > pressure, especially because weak points have been created , interms of
> > > > openings made in walls to fix the "hold fasts". So,my question is: do
> > >other
> > > > fellow engineers agree with this procedure Or they would like to suggest
> > > > some better  or alternative recourse?
> > > > SYED FAIZ AHMAD
> > > > SENIOR STRUCTURAL ENGINEER
> > > > SAUDI OGER LTD
> > > > RIYADH, SAUDI ARABIA
> > > >
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> --
> ++++++++++++++++++++++++++
> Forrest T. Braun, P.E.
> BBFM Engineers, Inc.
> Ph (907)274-2236
> Fx (907)274-2520
> Anchorage, Alaska
> http://www.bbfm.com
> ++++++++++++++++++++++++++
>
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