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Lintel over 14' opening
2

Lintel over 14' opening

Lintel over 14' opening

(OP)
This is the case:  Brick veneer wall on metal stud, over 14' garage opening.  There is 6' brick veneer wall above opening.  What is the best "lintel" for this situation?  I did a load calculation and came up with a W12X40 to support the 6' brick above.  There is a 24" between doors.  Can I support the I beam on the brick or do I need some other support?

Suggestions please.

Thanks in advance

RE: Lintel over 14' opening

Whats the weight of the brick veneer?

RE: Lintel over 14' opening

(OP)
Weight of brick = 40 psf

RE: Lintel over 14' opening

marthab,

A few things to consider:

1. When you say "brick veneer", to me that implies 4" face brick. A veneer is an architectural, not a structural element. Therefore I would not rely on it to provide structural support.

2. The W12 has an 8" flange width. I would try to provide a bearing surface of at least 8" if possible.

3. A W12x40 is a pretty large member to carry 6' of brick over a span of 14'. Is there other significant wall load that requires such a member?

Good luck.

RE: Lintel over 14' opening

Is there a roof load at the top of the 6' wall? 240 plf plus a dl plus a live load? could go as high as 300plf on that 14 ft. beam.

RE: Lintel over 14' opening

What is typically done with brick veneer that spans more than about 8 feet, is to drop support angles from the roof framing above, in line with the walls studs and these then support a "hung" brick ledger angle.  

Normally, we set the outside face of the vertical hanger angles flush with the outside face of the metal studs.  The studs will fill in between and around the hanger angles.  The ledge angle will then be welded to the hanger angles and be large enough to extend out to within about 1/2" of the outside face of the brick.  

With 6 feet of vertical drop, you will most likely need to have some kind of diagonal brace angles extending from your roof down to near where the hangers meet the ledger.

For openings less than about 8 feet, a loose steel angle is usually used, and bears on the brick each side.  More than 8 feet and you get a little shaky in that you are building up lateral wind forces in the lintel that try to transfer it to the studs located directly in the jamb areas of your opening.  The ties that link the brick to the wall backup are not intended to take this extreme amount of load...thus, hanger lintel design is required.

RE: Lintel over 14' opening

(OP)
Jae, it is a metal building structure.  The brick veneer wall is not a bearing wall.  It will carry the wind load on it but not dead or live loads other than its own weight.
Can the metal building manufacturer design the veneer support as part of their structural design?

Thanks again

RE: Lintel over 14' opening

In residential applications over garage doors I have seen 5x5x3/8" angle, with the brick veneer supporting the ends and the brick layed on the bottom leg.   Some times they have been bolted into the header some time they are free spaned.

Is that allowed by code?  

RE: Lintel over 14' opening

With a 14' span and only 6 feet of brick above the opening, you could try using a "loose" lintel, as suggested by boo1.  I would try to go a something with a 4" horizontal leg......L6x4x? or L8x4x?.

With a 14 feet opening and 6 high brick, you don't get any arching effect from the masonry (you usually need to be able to achieve a (2)-45degree triangles for arching to come into play), so you will need to design the lintel for the full weight of brick, ie....40 psf x 6 feet high = 240 plf.

Regarding reisting lateral wind load, since the brick is a veneer, the ties, which should be spaced 16" oc in each direction, transfer the wind load back to the wall framing.  Therefore, the lintel, in my opinion, does not need to be designed to resist the wind load.  The header in the metal stud wall over the garage dorr should be designed to resist wind load.

  

RE: Lintel over 14' opening

We like to use tube lintels so as to reduce torsional effects on the section (if loaded eccentrically, as they usually are).  I didn't run any numbers, but a W12x40 feels big.  What controlled design if you don't mind me asking?

Does your lintel attach to the metal building, imposing vertical and/or horizontal loads?  I would coordinate that closely with the manufacturer.

In fact, you bring up a good point: if it were me I would let them design the lintel in-house.  They know best how it affects the structure that it attaches to and will reduce the possibility for coordination problems.  Also, from a liability standpoint, say there is a problem later with cracked veneer.  Who is responsible?  The lintel designer? the purlin (stud back up) designer?  

Something to consider anyway.  Hope that helps.

RE: Lintel over 14' opening

(OP)
The design was:  M= W x L^2/8,   S = 12 M/Fb  and check deflection l/600.  Bending is the critical factor.

RE: Lintel over 14' opening

For this situation, a steel stud (I don't like the term metal stud) box header should be designed, by the stud supplier, to carry the brick.  A shelf angle, with outstanding leg long enough to pick up the brick, is welded to the box header.

DaveAtkins

RE: Lintel over 14' opening

Consider a jamb with depth equal to the metal stud wall + the veneer thickness to reduce eccentric column loading. It can help with the end closuredetail.

Also consider bracing the midspan or midpoints of the lintel back to the above structure to reduce torsion effects and increase the unbraced length strength of the beam.

RE: Lintel over 14' opening

DaveAtkins idea is a good one if you don't want to hang the lintel from the structure above.

For pre-engineered steel buildings you CAN detail the hangers and the building manufacturer should be able to incorporate it into the building details.  You would want to provide the hanger sizes, braces, and hanger loads, both vertically and laterally to them to design properly.

I would not use a loose lintel for a 14 foot opening unless you very carefully checked the entire load path and the torsional issues; including lateral force distribution.

RE: Lintel over 14' opening

JAE what limit could a loose lintel be considered.

Im my area the residential lintels are typically not Engineered, but selected by the brick mason or brick supplier.  The 5" angles are used becouse it matches flush the 4" brick veneer with 1" air gap.

RE: Lintel over 14' opening

I did the calculations and found that an L8X4X3/4 loose lintel works, with L/600 deflection being the controlling factor.  I still think the box header option is a better answer.

DaveAtkins

RE: Lintel over 14' opening

The structural concerns seem to be addressed above from many angles (no pun intended).  However, DO NOT FORGET TO DETAIL CONTROL JOINTS in the brick above each end of the lintel.  No matter how you design and detail the brick support structurally, there will likely be cracking in the brick above each jamb unless control joints are installed.

RE: Lintel over 14' opening

boo1 and DaveAtkins - I have always limited the length of loose lintels to about 8 feet, not because I can't get a lintel to span that far, but because once the lintel is installed, it depends on BRICK VENEER to take its own load.

This is problematic in that the brick has limited bearing capacity, a concentrated load is applied to the edge of the brick at the edge of opening and laterally, the only thing resisting buckling in the brick are wire or strap ties.  

I guess I'm just advocating that if you use a very long lintel, that the entire load path should be carefully considered...and this includes lateral wind/seismic forces that impose a load on veneer, through strap ties, and into metal studs (or whatever backup wall you have) - all of which should be carefully detailed -  much of which is USUALLY specified and detailed by architects.  Just be careful.  You can't just spec a loose lintel and stop there.

RE: Lintel over 14' opening

An L8x4x3/4 is a big angle.  You may have trouble hiding the 3/4 in a 3/8 mortar joint...

RE: Lintel over 14' opening

Thats why the residential guys use the 3/8" thickness.
You can saw cut the bricks to maitain the layo

JAE thank you for your reply.  But why does "it depends on BRICK VENEER to take its own load"?

RE: Lintel over 14' opening

I simply meant that a loose lintel is ultimately supported by the brick itself - the lintel spans loose from jamb to jamb and the brick edge receives the lintel load and distributes it downward, spreading out as it goes, to the support below.  So the brick weight above the lintel is transferred through the lintel and into the brick jamb area.

RE: Lintel over 14' opening

I prefer the plate welded to the bottom flange and sized for bending of the weight of the brick. The out of plane load must be checked together with the vertical load. That's another reason why the bracing is convenient.

The 40 pound wide flange won't substitute for the angle itself. You can check composite qualities though for the two pieces working together. The beam support column must restrain torsion as well as support the vertical load.

You still need the control joint.

RE: Lintel over 14' opening

Please note, the column provides stability for out of plane load. It spans to the roof or diaphram. Without it your wall has a knee joint in the middle.

RE: Lintel over 14' opening

I noticed you said this is a metal building, have you verified that the lateral deflection of the metal building has been limited for brittle wall finishes? The metal building guys like to play fast and loose and I'm betting they are letting deflection get as high as L/240 in the lateral deflection which will not be very friendly to your veneer.

RE: Lintel over 14' opening

(OP)
We are in the design process.  We are going to request that the metal building will provide lateral support for the brick veneer.

RE: Lintel over 14' opening

What about loose angles for hollow 8" cmu? Anybody using these and if so, what spans? You could have a little more twisting on the angle as compared to when you use them for brick.

RE: Lintel over 14' opening

I would not use a single angle to support 8" CMU.  Most of the time I use a W8 with a bottom plate, or a bond beam.

DaveAtkins

RE: Lintel over 14' opening

Dave,

I use L6X6X1/4 to support openings in masonry as a retrofit type lintel (when cutting an opening in existing CMU wall). I use expansion bolts to fasten the angle to the CMU and grout the cells above the opening. The angle is installed in place by sawing the joint between the blocks and before the CMU is removed for creates the opening. I have a detail to add the vertical bars on either side of the opening as well. Contractors do not like them but they do an excellent job after I insist on them following the detail. The steel angle will extend min. of 8 inches on each of the opening.

This design and detail worked well for me. However, I limit my MO to no more than 6 feet.

RE: Lintel over 14' opening

Well, if a loose lintel is good to support say 8 feet of brick, then why couldn't you support some smaller width of hollow cmu block?

If I estimate 8 feet of brick to be 40*8'*4'=1280 total lbs supported by the lintel (with corbeling). Then why not support say 4' of block, ie. 55*4'*2'=440lbs?

I would of course use a bond beam if new construction, but I a thinking about cutting a hole in an existing wall.

Just a thought.



 

RE: Lintel over 14' opening

The is the perfect situation for the light gauge specialty contractor to design ganged light gauge "jambs" and a light gauge box header across the opening.

You can screw attach a lintel angle to the light gauge header for brick support. Welding is possible, but special welding techniques must be met and your steel erector may have trouble meeting this requirement.

The only other practical option for this kind of span is to add structural steel tube posts on either side of the opening and span a HSS tube header across the opening with a welded brick support angle.

Good luck!

RE: Lintel over 14' opening

Keep in mind that the wind load on the garage doors needs to be carried to the roof diaphragm and the foundation by the jambs acting as vertical bending members on the sides of the opening.  For openings this large, I use channels for the jambs, and carry the lintel by the jambs.

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