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Re: CMU Wall Strengthening

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Scott,  Thanks again for your reply.

The one bay of the problem is a drive-in bay.  The truck pulls into the
warehouse about 30 feet to an interior loading dock.  Since the damage
indicates the movement is outward I would assume the truck pulling out of
the bay hit it.  Perhaps the door was lowered after a truck pulled in and
then reopened, but not fully, and the back hit the door?  Or perhaps
something stuck out of the truck bed?  I don't know.  Nobody is owning up
to it.  I just see the damage.

Since the wall is 20 feet tall I would not assume a 6" CMU with a
insulation cavity.  Since it is warehouse I would not assume any
insulation.

Thanks again.


Rich

On Wed, 10 Sep 2003 16:12:58 -0400 (EDT) Scott Maxwell
<smaxwell(--nospam--at)engin.umich.edu> writes:
> Rich,
> 
> I would still be somewhat careful about the determination of a 
> truck
> hitting it.  If the wall bowed inward, this would make a LOT more 
> sense
> (i.e. the truck backed into the door jamb).  Unless the truck 
> actually
> entered the building fully and struck the door when leaving the 
> building,
> how do you envision the truck stricking the jamb such that it would 
> cause
> the wall to bow outward?  I suppose that it could "brush" against 
> the jamb
> and by friction cause it to bow outward, but that seems to be at 
> least
> little bit of a stretch.  Could be though.
> 
> As to the wall construction, it sounds like you CMU could actually 
> be 6
> inch in width if the wall is non-composite.  Most non-composite 
> walls
> usually do have an air space/space for insulation.  On the 
> otherhand, it
> could be 8" CMU with a 3/4" collar joint (or so) to get your full 
> 12" wide
> (assuming that it is actually 12" rather than a nominal 12").  As 
> you
> point out, you should be able to really determine that after some of 
> the
> brick return in removed.
> 
> HTH,
> 
> Scott
> Ypsilanti, MI
> 
> On Wed, 10 Sep 2003, richard lewis wrote:
> 
> > I didn't clearly state what the steel lintel bearing condition is. 
>  The
> > brick wraps the jamb the 12" wall thickness.  You only see the CMU 
> from
> > inside the building.  The 4" bearing on brick is the 4" that wraps 
> the
> > jamb.  Then it extends 4" more onto the CMU.  When the brick is 
> replaced
> > 4" of the bearing length will be removed and 4" will remain.  I am 
> asking
> > for temporary shoring of the lintel until the brick is replaced.  
> I guess
> > the shoring should stay in place for a few days.  I can't tell hat 
> the
> > steel lintel is.  From the bottom I see a steel plate.  It is 
> buried in
> > the wall.
> >
> > I can't tell if there is a grouted collar joint.  It is not 
> exposed
> > anywhere.  Only after some of the brick is removed would I know 
> that.  I
> > would assume the wall is not composite for gravity loads, although 
> I
> > don't know the intentions of the original designer.  It is an old
> > building and there aren't any drawings around for it.  It is a 
> strip
> > warehouse.  Perhaps the designer used composite width for wind 
> loads.  It
> > is in East Texas so seismic is not a consideration.
> >
> > I think a truck hit it due to other evidence.  The steel track 
> jambs of
> > the overhead door were recently replaced.  How recent I was not 
> able to
> > find out.  All the other door steel jambs are painted.  This one 
> jamb has
> > not paint with some rusting.  The rusting is not that extensive so 
> I
> > think it is fairly new.
> >
> > Rich
> >
> >
> > On Tue, 9 Sep 2003 19:13:32 -0400 Roger Turk 
> <73527.1356(--nospam--at)compuserve.com>
> > writes:
> > > Rich,
> > >
> > > I have no suggestions on fixing the out-of-plumb wall, but I 
> would
> > > be
> > > concerned with the lintel bearing partially on the 4" brick and
> > > partially on
> > > the 8" cmu.  With the wall being 12" total thickness, it seems 
> that
> > > there
> > > isn't any room for a grouted collar joint.  Is the inside of the 
> cmu
> > > also
> > > bowing or is it just the brick wythe?
> > >
> > > At this point you probably should also look into why a truck 
> would
> > > hit/hook
> > > onto the wall.  If the doors with the loading dock have a 
> depressed
> > > ramp, it
> > > doesn't take too much of a slope (2:12) for the top of a truck 
> to
> > > project 2'
> > > beyond its bed.  If you don't provide for a dock extension and
> > > bumper system
> > > or large bollards, a truck is again going to hit the wall.
> > >
> > > HTH
> > >
> > > A. Roger Turk, P.E.(Structural)
> > > Tucson, Arizona
> > >
> > > Rich Lewis wrote:
> > >
> > > . > I have a shipping warehouse that has some problems with its
> > > masonry
> > > . > bearing wall.  The front of the building has 3 overhead 
> door
> > > openings.
> > > . > The wall is 12 inches thick, 8" CMU and 4" brick.  The doors 
> are
> > > 12 feet
> > > . > wide.  Two doors have a loading dock bumper height of about 
> 3
> > > feet high.
> > > . > A third door opens on grade and is 14 feet high.  All door 
> heads
> > > are same
> > > . > height.  The masonry pier between doors is 5 feet wide.  
> The
> > > remaining
> > > . > front of the building is a full height masonry wall for 
> about
> > > 100 feet in
> > > . > length.  The wall height above the doors is about 9'-8".
> > >
> > > . > It appears that a truck has caught the side of the tall 
> opening.
> > >  The
> > > . > masonry piers are out of plumb.  I dropped a plumb bob from 
> the
> > > roof to
> > > . > the door head and the top of door head is about 3/4" out of
> > > plumb to the
> > > . > exterior face.  I dropped the plumb bob from the door head 
> down
> > > to the
> > > . > ground and the wall went back in about 3/4".  The adjacent 
> door
> > > was
> > > . > similar, slightly less.  The pier between the last 2 doors 
> was
> > > about 1/2"
> > > . > out of plumb, same curvature as the first one.  As I 
> progress
> > > away from
> > > . > the 14' high opening the out of plumb decrease, so it 
> appears to
> > > radiate
> > > . > from this one door.  That's why I think a truck must have 
> pulled
> > > out one
> > > . > door jamb.  The top of this jamb has severely cracked 
> brick.
> > >
> > > . > My fix first is to repair the cracked brick.  The steel 
> lintel
> > > above the
> > > . > door bears 8" on the jamb, the first 4" being on the 
> cracked
> > > brick.  Then
> > > . > I think I should stabilize the masonry piers.  My thought is 
> to
> > > use a
> > > . > steel 'strongback' on the inside face.  I envision a steel 
> wide
> > > flange
> > > . > column bolted to the CMU wall.  I expect the top course to 
> be a
> > > bond beam
> > > . > since steel bar joist bear on it.  I can attach the bottom 
> to
> > > the
> > > . > concrete floor or a concrete wall at the base.  I would 
> guess I
> > > could
> > > . > connect to the masonry wall at about 2' o.c. vert. with 
> adhesive
> > > anchors.
> > >
> > > . > I want to get some feedback on what to design this 
> 'strongback'
> > > for.
> > > . > Perhaps some of you have done this before.  The strongback 
> will
> > > not be as
> > > . > stiff as the CMU wall so I don't believe it will take the
> > > lateral
> > > . > loading.  I guess it would just be for buckling 
> stabilization so
> > > the wall
> > > . > does not get worse.  What kind of forces would this be?  
> Would
> > > one
> > > . > strongback per 5' wide pier be enough?
> > >
> > > . > Thanks for your help.  I really appreciate all the wisdom 
> from
> > > your
> > > . > input!
> > >
> > > . > Rich
> > >
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