Steel HSS Cantliever and END plate connection

[Ramezsayed EIT]

Hi

I am designing a cantilever HSS and due to architectural reasons the client want the beam to be on the edge of the End plate per this picture.

I used STAAD Model to do 3D Free body analysis for this end plate with the HSS and there were no weird stress there. Is there any restrictions in the AISC code or any topics that discuss this eccentric loading case. the anchors were designed for this eccentric case as well and they are fine.
The end plate is the full length of the projected beams ( the cantilevers are spaced 48'' OC)

 

[KootK]

1) no restrictions that I'm aware of.

2) the eccentricity tends to exacerbate any innacuacies that might be associated with assuming the connection plate to be rigid if that is what has been done.

 

[Blackstar123]

I used STAAD Model to do 3D Free body analysis for this end plate with the HSS and there were no weird stress

You mean you made a finite element model of end plate with HSS modeled as plate elements instead of frame element?

no restrictions that I'm aware of.

Aren't AISC equation for thickness of end plate based on a well defined yeild mechanism for concentric case?
Wouldn't yeild mechanism in this case be different than for the concentric case?

Euphoria is when you learn something new.

 

[Blackstar123]

P.S. Do make sure to check the column for anchorage specially for the second case. In my opinion, edge distance is very small.

Euphoria is when you learn something new.

 

[dik]

Blackstar: If you're using yield line, yes, otherwise not very much. It's an easy connection; I'd likely use a stiffer end plate... maybe 3/4" and fillet welds as suggested by the AISC to develop full section capacity of the HSS section.

Dik

 

[Blackstar123]

Dik, I hear you but I'm still not sure. I'll need to do a little more study before commenting on this with any conviction.
But if cantilevers are not heavily loaded, then the minor eccentricity may be ignored.

About stiff end plates, although you may be on conservative side as far as thickness of plate is concerned but it'll increase the possibility of prying action in the bolts.



Euphoria is when you learn something new.

 

[r13]

In the lower case, it looks like only the upper bolt will be engaged in action, am I wrong?

 

[dik]

Blackstar... I'd prefer the stiffer connections... bolts are normally not an issue.



Dik

 

[Ramezsayed EIT]

I Attached the STAAD Model I did so you can see what happened and what did I do so you can give me your feedback

The line load is approx 10 Lb/in downward

The stresses increased on the upper bolt row as seen in the model and the plate is not considered as 100% fixed connection.

the deflection is around 0.67'' at the edge of the cantleiver ( Thats a canopy btw and every thing is ASD)

 

[JLNJ]

The bolts may pry which causes changes in your plate stresses and bolt forces.

 

[r13]

Is this a stress diagram, or force diagram?

 

[JLNJ]

looks like stresses in psi

 

[r13]

Then why the stress does not vary with beam depth?

 

[JLNJ]

It does, it's just that the stress in the entire member is so low (especially near the end) that it's all the same color. If the color gradations were finer the change in stress would be more evident.

 

[r13]

JLNJ,

Thanks. It makes sense.

 

[RPMG]

It's not eccentric. The load passes through the centerline.

The plate is too thin and too wide. It should be stout and an extension of the HSS. The flexural strength of the 1/2" plate is too low compared to the flexural strength of the HSS.

 

[r13]

RPMG,

I don't quite follow. Isn't there bending moment along the cantilever beam?

 

[Blackstar123]

Ramezsayed,
The views you provided in the first post were elevations? I thought they were plan views.
If its so, then I retract my concern voiced in previous post.

But agreeing with RMPG, your plates do seems a little too wide. If you are concerned about clearance requirement for bolt tightening, clear distance = 2dia of bolt from the hss will be more than enough

Euphoria is when you learn something new.