Masonry Wall Opening
Masonry Wall Opening
(OP)
I have a question on strengthing a masonry wall. I need to change two single doors (9'-0 span) to a single door by removing the pilaster between. I was going to span a channel as a header beam, and bolt into the precast headers over each door. The thing I am worried about is the torsion in the channel, and also if there will be torsion in the CMU that is left. There is about 4' of wall that the channel has to carry. Am I over anylizing this?






RE: Masonry Wall Opening
Normally when channels are used to accomplish this, they are placed flat with the flanges up, i.e., no torsion.
Normally for retrofit construction, I use steel tubes. These take vertical as well as horizontal loads well, plus, are inherently good to resist any induced torsion.
Mike McCann
McCann Engineering
RE: Masonry Wall Opening
If this is correct then the channel is acting on its weak axis, depending on the section size I would expect some bending.
I expect it will work and that if a crack appears above then it will be filled. The other option is to remove the lintels for the single door openings and replace with one new longer concrete lintel.
RE: Masonry Wall Opening
Hope this clarifies
RE: Masonry Wall Opening
A second solution is to use needle beams to support the wall above the openings, remove the existing lintels and wall in between the openings, install the new lintel, then remove the needle beams after the wall and lintels have cured and repair the wall where the needle beams went thru.
A third solution is to use channels on each side of the wall with thru bolts at 8 , 12, or 16 inches o.c. connecting the channels and supporting the wall above. At the end of the channels you will need to transfer the load back to the wall with thru bolts. The exterior channel will have to be covered if it is aesthetically objectionable.
RE: Masonry Wall Opening
Mike McCann
McCann Engineering
RE: Masonry Wall Opening
Bottom line (everyone here seems to agree) is that a steel lintel should not be installed on just one side of the wall.
And remember--try to develop a solution that is easy for the contractor to implement, but at the end of the day means and methods are his responsibility.
DaveAtkins
RE: Masonry Wall Opening
RE: Masonry Wall Opening
For channels: Install one on each face of the wall and through bolt. If desired a flat plate can be installed at the head after removal of the pier to clean up the appearance by welding to the channels.
For angles: Install one on each face and then weld a flat plate across the bottom from angle to angle after removal of the pier to brace the angles and prevent any possible shifting.
If the client will not accept steel on the outside of the wall, then you should shore the wall, roof, etc. and remove the old lintels and install a new masonry or steel tube lintel.
I would not recommend a single steel lintel on the inside face only.