Torsion on Coped Section in Single Angle Connection 1

[JA]

Hello,

I am designing single angle connections that are both bolted-bolted, or bolted-welded. The supported members are often coped at the top and bottom flanges. As such, is it is your opinion that torsion should be considered on the remaining coped section (effectively a thin rectangle) due to the eccentricity from the single angle? This often becomes very limiting as the remaining section has minimal torsional resistance.

Does anyone have any research or guidance on this matter? I have consulted the AISC manual for single angle connections with limited success as far as guidance on what/if torsional effects should be considered on the remaining section.

Thanks in advance.

 

[WARose]

The supported members are often coped at the top and bottom flanges. As such, is it is your opinion that torsion should be considered on the remaining coped section (effectively a thin rectangle) due to the eccentricity from the single angle?

No.

 

[CANPRO]

2nd vote for "no". I have a question though - if you have a single angle connection, why bother coping the top and bottom of the beam?

 

[dik]

If you're looking for a vote, a third 'No'. The striffness of the angle, relative to the beam is so small that as long as your bolts/weld can transfer the eccentric load from the fastener to the beam web, torsion is minimal. For torsion to occur, there has to be a rotational displacement.

Dik

 

[JA]

Thank you all for your feedback.

CANPRO, the top and bottom flanges need to be coped to allow for clearance past the flanges of the supporting member.

Either way it would seem that the general consensus is that torsion is not be considered in the coped section of the beam.

 

[canwesteng]

It's good that you're recognizing the eccentricity here, but most standard connections have been tested to failure so you should feel confident using the AISC published values.

 

[CANPRO]

JA, stupid question on my part - I have beam to column connections on my mind right now, which is why I asked.

 

[WARose]

Here is a good article on design of (single) shear tabs which is analogous to what you are talking about (it takes on the torsion issue):

https://www.aisc.org/globalassets/aisc/research-library/design-of-extended-shear-tabs.pdf

 

[dik]

thanks guy... good article.

Dik

 

[JA]

No worries Canpro.

Thank you for the article, that was very helpful. Reading through the article would suggest that torsion should be considered; however, with non-extended configurations the torsion does not need to be considered. In the case of a single shear tab the torsion is quite minimal, however in a bolted-bolted connection the eccentricity could be much larger (say in the 2-2.5 inch range for a typical angle). This would lead me back to thinking that torsion should be considered...even though it is not an extended configuration.

Maybe overthinking it now, but just want to ensure I have it straight.

 

[JA]

One other thing to mention as well. The AISC tables for bolted-bolted connections don't include tabulated values for angle thickness, effects on copes, etc. They simply only have tabulations for bolt eccentricity considerations. Does anyone know if these have been tested and it has been proven that the bolts will always be the limiting factor?