Narrow Tee Connection to HSS Subject to Axial and Shear 1

[azogr]

I am considering a couple unusual connections for a small steel framed pergola with light loading. Have any of you ever designed a narrow tee connection to an HSS subject to shear and axial load? The worst case loading will be light, only 3.4 kips of shear, and 1.72 kips of axial load. See any reason to avoid this proposed connection below given the light loading? The customer specifically requested avoiding a through plate connection.

 

[strucbells]

Detailing looks ok for those loads...tiny bit of eccentricity for the axial load, but prob not a big deal given the magnitude of force and some assumed dimensions here. Do you really need (3) 3/4" DIA bolts for those loads? Is that geometry driven based on beam depth controlled by deflection?

Have you considered just welding the HSS beam directly to the face of the HSS column? Maybe there's no way to avoid field welding if you go that route (depending on rest of framing layout and connections). It would be more of a moment connection and there may be some expansion/contraction consideration if this thing is outside and in direct sun depending on how long it is, but it would be simpler if it could be shop welded.

 

[r13]

It is fine, but why not weld the beam directly to the column? I don't quite follow the saddle connection, isn't that with two through bolts?

 

[strucbells]

Depending on your HSS wall thickness and dimensions, you could probably also just shop weld a shear tab and get rid of the reinforcing plate at the column face for those loads. Use Chapter K of the steel manual to check the HSS wall to confirm.

 

[azogr]

Do you really need (3) 3/4" DIA bolts for those loads? Is that geometry driven based on beam depth controlled by deflection?

No, I don't need three bolts and you are correct, more driven by geometry. Two just looked a little small to me given the geometry.

Have you considered just welding the HSS beam directly to the face of the HSS column?

Yes, I had considered,but the customer wanted to try to avoid as much welding in the field as possible. Given the configuration of the structure most, if not all, of these connections will need to be made in the field.

I don't quite follow the saddle connection, isn't that with two through bolts?

Yes, I probably should have given a little more explanation on that one. The beam needs to cantilever over the column, hence the saddle. Yes, I was planning on through bolts. I had considered a cap plate and an plate welded to the bottom of the HSS beam and bolting the two together, but I was concerned about fixity and opted for a saddle.

I appreciate the comments and the sanity checks! You're right strucbells, I probably could go back to a shear tab on the column. I hadn't determined the demand on the connections when I was working out options with the client and I was worried about the thin walls of the HSS (0.116") so I proposed the narrow tee.

Thanks again for taking the time to respond!

 

[strucbells]

Phew those are some skinny HSS walls! 1/8" A500 tube with the 0.93 reduction? Don't blame you for reinforcing the face, even if it may calc out without it. Make sure they don't pretension your through-bolts and crush the hss section for the cantilever detail.

Sounds like you have it pretty well figured out.

 

[azogr]

Good point! I had a snug tight note on my other through bolt connection (not shown) but forgot to add it on this one. thanks!

 

[dhengr]

Azogr:
What provides any lateral stability for this pergola? Maybe the beam to column connections should be moment connections. Provide small drain holes at low point in the members.

 

[azogr]

What provides any lateral stability for this pergola?

Fixed base columns