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CMU Wall Strengthening

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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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