Single-angle loose lintel design 1

[legner]

I am wondering how others design single-angle loose lintels:<br><br>1. Use BIA tables?<br><br>2. Design for l/600 deflection and check fb&lt;=0.6Fy?<br><br>3. Design per single-angle specification, accounting for eccentricity of load, torsion, tip deflection due to torsional rotation, etc?<br>&nbsp;

 

[Imagineer]

I don't think I've ever used a single angle.&nbsp;&nbsp;Because steel is cheap, I've either used a double angle or a wide T section.&nbsp;&nbsp;Do you have something restricting you to the use of a single angle?<br> <p> Imagineer<br><a href=mailto: > </a><br><a href= > </a><br>

 

[legner]

I'm talking about a single wythe of brick (3 5/8&quot with a loose steel lintel. A double angle would not fit.

 

[faf]

I've never spent a lot of time designing lintels.&nbsp;&nbsp;The masonry arches above the opening so you end up with a triangle of load above.&nbsp;&nbsp;A rule of thumb that I've never had a problem with is to provide one 3 1/2 inch horiz. leg angle for each wythe of masonry.&nbsp;&nbsp;The vertical leg of the angle is equal in inches to 2/3 of the length of the opening in feet or the vertical leg of the angle times 1.5 will give you the allowable span.&nbsp;&nbsp;In other words and angle with a 4 inch vertical leg will support one wythe of masonry over a 6'-0 opening.&nbsp;&nbsp;Inasmuch as there is no such thing as a 4 x 3 1/2 inch angle, I would use a 5 x 3 1/2 x 5/16 angle.&nbsp;&nbsp;I always have used 5/16 thickness allowing a 1/16 for corrosion inasmuch as 1/4 is enough thickness for strength.&nbsp;&nbsp;As you can see, spending a lot of time on design isn't productive because angles are cheap for what they do and there are not many size choices that would justify an exact analysis.&nbsp;&nbsp;&nbsp;&nbsp;

 

[wwjk]

I usually count on arching action of the brick and then have the Architect place control joints on both sides of the opening to allow for good movement.

 

[JAE]

wwjk: I'm not sure that works. To get arching action in masonry, you must have masonry on either side to take the lateral thrust from the arch. If you add control joints on either side, you've essentially eliminated any lateral thrust action.

If you need a joint, you can place one on one side only. The masonry will tend to arch to one side (although there still is no real arch action) and you can design the lintel for a triangular load, with the peak of the triangle at your control joint side. We usually use a 1:1 slope line to estimate the weight of the brick/block on the lintel.

 

[ishvaaag]

In any case I have posted Mathcad worksheets of free download that check the strength of angles and double angles both in flexure and biaxial flexocompression.

 

[quosco]

Where are these downloadable Mathcad worksheets ishvaaag is talking about? I am having the same problem convincing a fellow engineer that steel lintels supporting brick veneer need to meet an L/600 deflection limit. These worksheets would definitely help. Any further info would also be appreciated.

thank you

 

[haynewp]

The footnotes on Table 1 of BIA technical notes 31B states that deflection is limited to L/600 and fb=22KSI. This table assumes full arching action (this means no joints on the sides of your opening). There are other important footnotes you should also read here. This table is what I use after researching this same issue.

I beleive the mathcad forum ishvaaag was referring to is

http://collab.mathsoft.com/~mathcad2000

Search under keyword &quot;lintel&quot; and it will come up.
I think he no longer visits these forums.