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Re: CMU Wall Strengthening

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Rich,

A truck hitting the door or door opening makes much more sense now that I
know that trucks actually pull into the building.  It is certainly very
possible that a short delivery truck pulled in and someone unthinkingly
partially closed the door.  Then the truck pulled out hitting the bottom
of the partially closed door.  This will also make sense with the maximum
"bow" near the top of the door...if such a scenario played out.

The other thing that you could consider doing is installing what my old
boss referred to as a "goal post" to be used at the door frame.  This
would be two vertical tubes at the door jambs with a horizontal tube at
the top of the door opening.  The two vertical tubes would tie to the
floor and roof structure, which could allow them to be isolated from the
exterior wall...at least structurally.  Of course, this might mean needing
to do some undesireable things with the garage door itself (i.e. replacing
with new at worst or maybe just taking it out and re-installing to the
tubes...assuming that the door would work in such a situation).  You then
design the tubes to take the door loads and such.  That still doesn't
solve the bowing masonry though, no does it?!? ;-)

HTH,

Scott
Ypsilanti, MI


On Thu, 11 Sep 2003, richard lewis wrote:

> 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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