Unequal Leg Single Angle Design Software

In Elements you could take to a shell approach and model it that way instead of linear beam elements.

The McNulty Book is a good resource: Link
I think it used to come with a CD containing associated spreadsheets but recent reviews seem to indicate that needs to be purchased separately now.

My Personal Open Source Structural Applications:

Open Source Structural GitHub Group:

My strong suspicion is that nobody wants to touch lintel design for fear that, no matter what they do, a bunch of folks will think that it's wrong. The complexities abound:

1) Pretty much no way to load an angle that doesn't wind up biaxial.

2) The bearing reactions are not coincident with the shear center so you've got weird torsion in the member, and in the bearing stress checks.

3) Issues regarding how much load the angle is really taking with respect to brick arching, control joint locations etc.

4) One ought to consider twist in addition to vertical deflection.

When I moved back to Canada after starting my career in the US, I was pleasantly surprised to find that Canada's code has something for this. How they arrived at it, I don't know. And I don't much care. It seems fairly aggressive and I figure that, if zillions of buildings have used these lintels, my odds of success are good.

This is actually on my Kootware todo list.

McNulty breaks it down easy enough to make your own spreadsheet.

KootK... that's from Part 9 for houses and small buildings.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

dik said:

KootK... that's from Part 9 for houses and small buildings.

Click to expand...

Well, yeah... that's where I got it from.

5) The load migrates closer to the vertical web as the the angle rotates. Better for the angle, worse for the brick.

6) Local flange bending and the bearing location.

7) Because the angle twist is more in the middle than at the ends, applied torque is at a varying eccentricity as you got.

Conservative checks can be done for most of this stuff but, then, that tends to rule out a lot of what seems to work in practice.

8) Is the lateral movement of the angle really restrained by the brick ties and shear friction at the grout interface?

What do we think about using only the vertical leg shape for analysis, and ignoring the horizontal leg's contribution? And limiting the stress to Class 1 (compact)?

The Brick Industry Association (BIA) has a nice summary design guideline for steel angles supporting masonry.


An excerpt below.
The allowable stress, Fb, for ASTM A 36 structural steel is
22,000 psi (150 MPa) for members laterally supported.
Solid brick masonry walls under most conditions provide
sufficient lateral stiffness to permit the use of the full
22,000 psi (150 MPa). This is especially true when floors
or roofs frame into the wall immediately above the lintel.
The design for non-laterally supported lintels should be in
accordance with the AISC Specification for the Design,
Fabrication and Erection of Structural Steel for Buildings.

My experience with the Canadian code tables is mixed. The Code does not explicitly say it, but the tabulated lintels for masonry veneer assume that arching action can develop. So, if you have window openings in the masonry above the lintel, or small distances to the side of the opening beneath the lintel (no resistance to the thrust), then the tables should not be used ... but they are. These tables would also assume that a loose lintel supporting masonry veneer is considered to be laterally supported, thus simplifying the calculations significantly.

atrizzy said:

What do we think about using only the vertical leg shape for analysis, and ignoring the horizontal leg's contribution? And limiting the stress to Class 1 (compact)?

Click to expand...

I'm fine with it if it actually produces practical results. Do you know if it does? That's obviously going to rob you of a lot of yoru Ix / Sx and turn a blind eye to any torsional effects. When I'm outside the range of the tables that I use, I usually just design to L/600 vertical deflection, use an angle thickness of 5/16" min, check bearing, and leave it at that. That's probably not much different from what your proposing in concept.