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Re: Bomb Shelter

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FORREST
Now, its clear. Thank you forrest, 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: Sat, 02 Jun 2001 12:49:07 -0800

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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> >BBFM Engineers, Inc.
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> >http://www.bbfm.com
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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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