Shear Tabs on HSS columns

[SteelPE]

This is driving me a little crazy.

I am looking to design a tab plate off the face of a HSS column that is subjected to an eccentric shear load together with a tension/compression load. I am wondering if chapter K of the AISC manual addresses the instance when you have both eccentric shear and a T/C force? If not, how do you specifically address this issue?

 

[BAretired]

Ensure that:

t_p < {F_u0/F_yp}t₀

BA

 

[connectegr]

There may be an example in Design Guide 24. I have a program for these connections, but I cannot look at the references from my iPad.

http://www.FerrellEngineering.com

 

[SteelPE]

connectegr

Good reference. While it came close to answering the question it didn't quite. They used basically the same equation I did (equation K 1-9 of the 13 edition manual) to calculate the capacity of the plate with a load on an angle.

 

[abusementpark]

Do these single plate connnections provide enough torsional restraint to brace the top of the top column?

 

[BAretired]

A shear tab connection primarily resists vertical shear. The equation I gave earlier was Equ. 9.8 from "Hollow Structural Section Connections and Trusses" by Packer and Henderson.

When testing this type of connection, they found only one limit state for an HSS column. This was a punching shear failure related to end rotation of the beam when a thick shear plate was joined to a thin walled (Class 4) HSS. A simple criterion to ensure that the tension resistance of the tab is less than the shear resistance of the HSS wall (per unit length). This led to the equation given in my earlier post.

Yield line distortion of the HSS wall was never a critical limit state because the end slope of a simply supported beam is limited. However, if the shear is accompanied by axial force, the wall of the HSS must be capable of resisting the axial force. This can be determined using a yield line analysis.



BA

 

[RFreund]

Several good references:

http://www.modernsteel.com/steelinterchange_details.php?id=633

http://www.eng-tips.com/viewthread.cfm?qid=267808

http://myweb.msoe.edu/~raebel/Scott Thompson Thesis 07-09.pdf

EIT

http://www.HowToEngineer.com

 

[connectegr]

In this case yield line of the HSS wall is a limit state. Punching shear is the only limit state when loading is shear only. The addition of axial load requires the yield line analysis.

http://www.FerrellEngineering.com

 

[slickdeals]

I think hokie66 had posted about using a knife plate in a slot through the HSS.

It’s no trick to get the answers when you have all the data. The trick is to get the answers when you only have half the data and half that is wrong and you don’t know which half - LORD KELVIN

 

[BAretired]

A through plate is needed for a shear tab when the HSS wall is too thin, but it would not be too good if there is axial force in the beam.

BA

 

[hokie66]

Why is that, BA? If it goes through the hollow section, it engages both sides, so is at least twice as good for axial force.

 

[BAretired]

Hokie, my thinking was that the wall of the HSS would be cut to permit insertion of the through plate, so it is not continuous. Admittedly, it is welded to the through plate, but likely not enough to develop its bending strength.

With significant axial force present in the beam, a double angle or tee connection seems more suitable and probably more economical.

BA

 

[hokie66]

Maybe. We use a lot of those knife plate connections for heavy bracing. I haven't looked at the basis in some time, but think the CIDECT Design Guides are the main source.

 

[hokie66]

200 pages of reading here for anyone who is interested. For the US readers, there are references to AISC throughout the text.

 

[connectegr]

Typically the axial load in the connection is the transfer force. We can have a long discussion about the difference in the beam internal axial force and the required connection transfer force. If a thru-plate is used typically the forces is passed through the plate to the beam on the far side. If the connection is one sided, then the existence of a transfer force is another debate. This axial load would create a large column moment.

There are cases where the axial load (not transfer force) is a connection force. For example the shear and axial forces in the UFM bracing design.

In either case yield line analysis of the HSS wall is required to determine the adequacy of the column wall for the axial load. If necessary a reinforcement plate can be added to provide adequate capacity. As mentioned above a thru-plate may not be an adequate alternative.

http://www.FerrellEngineering.com

 

[BAretired]

Perhaps a specific example would be something we could all comment on.

BA