Connection between hollow section and channel beam

[Andrew88]

Hi all,

I need to connect hollow section with a channel beam as per attached drawing.

The hollow section is 150x100x6 and channel profile 150x75x18. They made part of the structure supporting checker plate flooring that will be bolted down to top flanges. I believe I can treat it as a pinned joint and for this situation the vertical shear force is 10 kN. This force acts in the centre of the hollow section profile so I ended up with a small torque of 10*100/2 = 0.5 kNm. Can I disregard it?

For bolts I assume that the shear force acts along the centroid of the channel section. Hence I get eccentricity between the centroid of channel and centroid of bolts and seize bolts for force coming from both shear and bending.

Would it be the same for calculation of the moment acting on the weld? My eccentricity now becomes the distance between channel centroid and weld centroid?

Thank you very much in advance,
Jed

 

[MER3]

Why not just flip the channel over and weld it to the HSS?

Without a sketch of the framing it is hard to visualize what you are describing regarding loads

 

[BAretired]

That looks terrible. Can you come up with a symmetrical connection?

BA

 

[StrucPEng]

Is there a reason you chose the profiles that you did? It seems you have chosen two of the more difficult profiles to detail and fabricate connections for (in my opinion) and that this could be accomplished much easier with WF sections.

What about welding angles to the HSS that are field bolted to the channel sim. to the attached. Obviously the particulars of the connection are for you to figure out. This would also get rid of your torsion issue.

 

[CANPRO]

I like the detail provided by M_S. You could also weld a single angle or a WT to the end of the HSS and use that to bolt to the shear tab.

 

[rb1957]

I quite like MS's sketch, except how to you control the squareness of the welded brkt flange to the supporting structure ? I'd rather field bolt both sides of the connection (or field weld to the tube) ... but then I don't work in this field (so what do I know ?)

another day in paradise, or is paradise one day closer ?

 

[StrucPEng]

rb - Generally any good fabricator should make that connection straight enough to bolt up in the field without much issue but good question none the less.

Your question did remind me that the detail will be hard to erect depending on what the other end of the beam looks like. It will be really hard to get that HSS in there if the other end is the mirror image.

I do like what CANPRO said with the WT welded flat to the end with the stem outward to connect to the shear tab. I have seen that before as well and its a pretty nice connection and makes erection easier than my previous post when they swing in the HSS.

Matt

 

[rb1957]

yes, welding a stub onto the end of the tube would be easier to erect.

another day in paradise, or is paradise one day closer ?

 

[BAretired]

I like the M-S detail. I don't understand the squareness objection. There IS a field bolt each side of the HSS and field bolting is preferred over field welding.

BA

 

[hokie66]

Hardworker87 had the best suggestion. Turn the channel around. When possible, it is always best to connect nearest the shear centre of a member, e.g. on the flat of a channel. Use an end plate on the RHS, and 2 bolts to the channel web.

 

[rb1957]

the squareness is between the two flanges being bolted together. If not true then clamp up stresses will be induced. I guess the end face of the welded brkt can be controlled in fabrication.

Also, I won't weld brkts to both ends. Won't that constrain the length of the beam ?

another day in paradise, or is paradise one day closer ?

 

[BAretired]

For this connection, flipping the channel works best, but it may not work for other connections along the length of the channel. We do not have the framing plan.

BA

 

[structuralsteelhead]

And with regards to Welds: Basic premise for hand solution, SRSS about all three axis considering shear, moment, torsion divided by respective resisting normal and polar moments of inertia. If you eliminate the eccentricity of the vertical force as recommended in all suggested connection variations above, you'll be able to use eccentric weld group tables to calculate weld stress directly since your torsional forces now limited to a single axis.

If you were to keep your offset connection, it would induce warping stresses to a degree that should not be ignored and I would think a FEM model necessary unless you have the skills or references to tackle that by hand. I do not. Maybe Mr. Lincoln (Arc Weld) would address these forces numerically. Agreed as stated above, provide symmetry in the connection and field bolting of parts.

 

[hoshang]

Hello
What about using a smaller shop welded hollow section sleeve (with a plate on one side) inside the 150x100x6mm hollow section and field bolted to the 150x75x18mm channel?