Braced Frame Connection (Gusset to HSS Column) 1

[tonycampos88]

Hello,

1. I have a SCBF connection and I'm trying to design the gusset-to-column connection. In watching a couple of seminars, I realized that the Uniform Force Method is not recommended for HSS columns as the column horizontal force might be too large for the HSS wall. In using the KISS method I come up with a very large (and long) gusset plate-to-column weld. So I started thinking again in the UFM. How can I actually check a concentrated load on an HSS wall? Does anyone have a design example for this?

2. Is it possible to have a drag strut-to-column connection through a single shear tab? What are the limit states for this connection?

Thanks!

 

[jittles]

Check your AISC 360, section K, for welds of plates to HSS. It covers many different configurations.

I typically design drag strut connections through a single shear tab. It's all the usual connection limit states, just with an added axial seismic component to the load on the connection. Your single plate connection is then part of the SLRS, which has specific welding and bolting requirements.

Both of these are usually a toss up on whether or not the face of the HSS will work. The gusset connection is more likely to work (longer connection, thicker walls typically), although I have seen some firms that always knife their plates through an HSS column, whether or not the chapter K limit states check out for a face connection.

 

[SteelPE]

I have run across similar problems with HSS braced connections. I found some better information in the AISC Design Guide 24..... or at least I have found some clearer information in the DG vs AISC 360. The problem you have with tabs is the fact the you tend to have shear, axial load and bending in the tab and more importantly the weld/HSS wall. Thru plates may help, but it's going to depend on how you look at the connection.

 

[SAIL3]

I try to bypass chpt K whenever possible...so I use a backing pl on the tap which also allows one to design the col for it's loads and not have to revisit the col design @ every conn...also knifeing the plates can be expensive....

 

[RFreund]

@sail can you expand on that detail. I don't think I understand.
thanks

EIT

http://www.HowToEngineer.com

 

[steellion]

Can you detail the plate to slot through the HSS column rather than attach to the HSS column wall?

 

[SAIL3]

The shear tab & backing pl looks like a fabricated TEE-section in X-section.....

 

[RFreund]

Sail - Thanks. So is the backing plate on the inside face of the HSS? Sorry I'm trying...

Also for those who recommend the through plate - Aren't the forces still transferred to the column wall; it's just now transferred to the front and back face?.

Thanks! (don't me to hijack the thread here...)

EIT

http://www.HowToEngineer.com

 

[SteelPE]

Again, I suggest looking at Design Guide 24. This guide will give the capacity of the tube wall for a welded tab and a thru plate (if I remember correctly is 2x the welded tab). The equations found in the DG can be found in chapter K but they are expanded upon slightly.