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Re: CMU Wall Strengthening

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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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