Single Angle Design Based on the Steel Construction Manual, 13th Ed.
Single Angle Design Based on the Steel Construction Manual, 13th Ed.
(OP)
I have two questions regarding single angle design. First question is in Part 16 Section F10.2. The yield moment is specified for section (i) and (ii) but not for (iii) and (iv), so I assume the yield moment is calculated using the principal axis for (iii) & (iv)?
Question 2.
Say I have a beam that is a single angle (similar to a lintel supporting brick above an opening).The brick load does not pass through the shear center of the single angle causing torsion. The single angle has no lateral-torsional restraint in between the supports. So I have flexural, shear, and torsional stresses. Part 16, Section F10 is for flexure of single angles, Section G4 is for shear of single angles, what about torsion? Would this scenario be Section H3.3? Say I can restrain the angles at the supports for all the reactions including torsion.
I don't know if this is standard but I seen it many times where the single angle lintel carries the brick above a small opening and it just bears on brick 8 inches on each side without any lateral-torsional restraint. Many architects show this feature on their arch details. Most details I have seen have a structural wall, then about a 1-inch gap and then the masonry veneer. And at an opening it has a steel angle supporting the veneer with no attachment to the structural wall. Is the steel angle required to have some type of lateral-restraint because if an angle just bears on the brick how is the torsional restraint achieved at the ends?
Regardless if I have a single angle lintel or not, if I have flexure, shear and torsional stresses acting on a single angle what do I check for torsion, H3.3?
Question 2.
Say I have a beam that is a single angle (similar to a lintel supporting brick above an opening).The brick load does not pass through the shear center of the single angle causing torsion. The single angle has no lateral-torsional restraint in between the supports. So I have flexural, shear, and torsional stresses. Part 16, Section F10 is for flexure of single angles, Section G4 is for shear of single angles, what about torsion? Would this scenario be Section H3.3? Say I can restrain the angles at the supports for all the reactions including torsion.
I don't know if this is standard but I seen it many times where the single angle lintel carries the brick above a small opening and it just bears on brick 8 inches on each side without any lateral-torsional restraint. Many architects show this feature on their arch details. Most details I have seen have a structural wall, then about a 1-inch gap and then the masonry veneer. And at an opening it has a steel angle supporting the veneer with no attachment to the structural wall. Is the steel angle required to have some type of lateral-restraint because if an angle just bears on the brick how is the torsional restraint achieved at the ends?
Regardless if I have a single angle lintel or not, if I have flexure, shear and torsional stresses acting on a single angle what do I check for torsion, H3.3?






RE: Single Angle Design Based on the Steel Construction Manual, 13th Ed.
2) You are still bending about a geometric axis, and F10 deals with this using Me. As long as you don't have some ridiculous eccentricity, I believe you are ok neglecting the torsion and using F10 as-is.
RE: Single Angle Design Based on the Steel Construction Manual, 13th Ed.
RE: Single Angle Design Based on the Steel Construction Manual, 13th Ed.
Analyzing a single angle in flexure is really not th easiest task in the world to do from a mechanics standpoint, but I believe AISC takes those pesky mechanics issues off the table with the design provisions.
RE: Single Angle Design Based on the Steel Construction Manual, 13th Ed.
RE: Single Angle Design Based on the Steel Construction Manual, 13th Ed.
RE: Single Angle Design Based on the Steel Construction Manual, 13th Ed.
RE: Single Angle Design Based on the Steel Construction Manual, 13th Ed.
I think this is exactly the case you'd have.
RE: Single Angle Design Based on the Steel Construction Manual, 13th Ed.
RE: Single Angle Design Based on the Steel Construction Manual, 13th Ed.
RE: Single Angle Design Based on the Steel Construction Manual, 13th Ed.
Thanks for the help guys and/or gals. I have enough information for what I have been looking for.
RE: Single Angle Design Based on the Steel Construction Manual, 13th Ed.
RE: Single Angle Design Based on the Steel Construction Manual, 13th Ed.
RE: Single Angle Design Based on the Steel Construction Manual, 13th Ed.
If the brick above the opening aligns with the supporting brick, torsional restraint is not required at the ends because the reaction is centered on the brick, i.e. the bearing pressure under gravity load is uniform.
The torsional moment in the angle at the support is R*e where R is the reaction and e is the eccentricity from center of brick to heel of the angle. Torsion is felt by the angle because its shear center does not align with the reaction. Torsion is not felt by the brick supporting the angle.
Torsional rotation is zero at each support and maximum at midspan. The rotation and torsional shear stresses can be easily calculated.
Wind loads on the angle, however, must be resisted by some form of lateral bracing to the structure.
BA
RE: Single Angle Design Based on the Steel Construction Manual, 13th Ed.
I kid somewhat...i understand the concern and the wanting to know the subject thoroughly.
RE: Single Angle Design Based on the Steel Construction Manual, 13th Ed.
RE: Single Angle Design Based on the Steel Construction Manual, 13th Ed.
http://www.gobrick.com/html/frmset_thnt.htm
To provide torsional restraint I usually just redhead in an expansion bolt at 2 to 4 feet on center. Keep in mind too that brick ledger angles only have to carry the weight of a trangular portion of the brick weight above due to arching action.
John Southard, M.S., P.E.
http://www.pdhlibrary.com
RE: Single Angle Design Based on the Steel Construction Manual, 13th Ed.
The above (posted by Southard2) is true but I want to point out a "problem" that I have seen numerous times when there is not adequate brick above the lintel to create such "arching action. There are a few different scenarios that cause a lack of arching action such as insufficient height or unsymmetrical layout or the odd location of a window above the lintel.
Just want to highlight this issue...
RE: Single Angle Design Based on the Steel Construction Manual, 13th Ed.
For anyone that is an AISC member, this article (and many more) can be downloaded from aisc.org by clicking on "ePubs".
RE: Single Angle Design Based on the Steel Construction Manual, 13th Ed.
as houseguy mentioned, remember the science behind the arch. I would suggest the mortar even has some tensile capacity and thus, almost no angle is needed in many occasions.
And I agree, I wouldn't turn this into a science project either, oversize the angle enough so you can neglect torsion. Recognize that the brick will help to resist torsion, and don't spend too much time on the design because it is just an angle. If you upgrade the angle to and 4x4x3/8 instead of a 3x3x3/16" and spend 1 or 2 hours less design time your client will still be ahead.