Lintel over 14' opening 2

[marthab]

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

 

[boo1]

Whats the weight of the brick veneer?

 

[marthab]

Weight of brick = 40 psf

 

[MotorCity]

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.

 

[dicksewerrat]

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.

 

[JAE]

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.

 

[marthab]

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

 

[boo1]

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?

 

[CSEllc]

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.

 

[ml13]

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.

 

[marthab]

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

 

[DaveAtkins]

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

 

[AlohaBob]

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.

 

[JAE]

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.

 

[boo1]

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.

 

[DaveAtkins]

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

 

[epr]

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.

 

[JAE]

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.

 

[LPPE]

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

 

[boo1]

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"?