single angle connection, angle welded to support beam

[structural001]

Hi - was hoping to find a design example of a single angle connection, where the angle is welded to the support beam and bolted to the support. The aisc examples and tables only seem to address bolted/welded connections where the angle is bolted to the support beam and welded to the support. Thanks for any help

 

[phamENG]

If you want to weld it to the supporting member, why not use a single plate shear tab?

 

[structural001]

The support in this case is a concrete wall. The purpose of the angle is to accommodate the wall attachment between the web of a C-channel and wall.

 

[phamENG]

Ah. I see. Your OP seems to be a little mis-worded. Should probably be "angle is bolted to the supporting concrete wall and welded to the supported beam.

Best bet is probably to do either a bolted/bolted connection or use an embed plate in the concrete that you can weld the shear tab to.

One of the reasons you always see bolts in the plate/angle to beam connection is that without them you don't have a shear only connection. These connections depend on something called "bolt plowing" at ultimate loads to allow sufficient rotation between the beam and the supporting column/wall/whatever to make it ductile and "simply supported." You may still get that in a bolted/welded angle with the welds on the beam through plastification of the angle and bending at the heel of the angle. But you'd better make sure the anchorage is stout so it doesn't rip out of the wall first.

If you're going to continue down this road, you'll probably have to rationalize the connection without the help of a design guide.

 

[Enable]

phamENG: This is conventionally what we've been taught but since lab testing has shown welded-welded shear tabs to exhibit as much rotation as their bolted counterparts I am a little less leery of a weld-weld shear tab condition. See here for example:

https://escholarship.mcgill.ca/concern/theses/k643b5288

To be sure in that thesis they only tested retrofit welds (so the tabs already had bolt holes in them) and that no-doubt allowed more deformation/rotation to take place above a solid plate (how much though?).


CWB (W47.1) Div 1 Fabricator
Temporary Works Design

https://www.enable-inc.com/

 

[phamENG]

Enable - thanks for that. I agree that it can be done, but it does go against the 'conventional wisdom' and, as such, deserves closer attention to the details and how the welds are specified to make sure you fit within the parameters of those studies. They haven't made their way into the wider body of accepted design practices yet so it pays to be careful with those details. I generally prefer to keep that in my back pocket to deploy as a repair if something goes wrong with fit up in the field.

Since the OP was looking for an example of the design, ostensibly to follow along in the design of their current connection, it might not be good to venture too deep into those weeds...

 

[Ron247]

AISC tends to not address attachment to another materials. Look in the concrete world for that side of the attachment. Welding the "supported beam" to the angle should not be that hard to figure out.

 

[ProgrammingPE]

Attached is an example calculation for a single-angle connection that is welded to the supported beam and bolted to the support. The check for the welds uses the same methodology that is used for double-angle connections that are welded to the supported beam per Table 10-2 (Welds A), except that the capacity is half since there is only one angle. The check for the bolts uses the same methodology that is used for single-angle connections that are bolted to the support per Table 10-11 (Case I).

I think it's also important to reiterate what phamENG said since you are attaching to concrete. You will get some rotation at the support due to the angle heel rotating, but it is still likely that there will be some tension in the bolts (even though conventional calculations don't typically consider this), so make sure you have enough anchorage to support any potential tension.

Structural Engineering Software:

http://www.structuralcentral.com

Structural Engineering Videos: www.youtube.com/channel/UCOj2mXXf3ZbZtgxTc6BtkGg

 

[robyengIT]

Some suggestions of the connection released few years ago (let's say like SlideRuleEra)in Italy by a research authority