Beam Clamp

[dylansdad]

I need to hang a structure (lightweight) under existing roof framing trusses. I have envisioned a hanger assembly which will clamp to the bottom flange. I have questions regarding how to analyze such an assembly.
1. Would there by any prying action to speak of?
2. Other than flange local bending are there any other limit states to check?
3. I am thinking pre-tensioned bolts for this arrangement (this will support moving equipment).
Thanks for your responses.

 

[rb1957]

FWIW ...

i don't like the way your bolts overhang the existing flange ... why not bolt through the flange ? i guess it's something about mixing wood and steel ??

do you have the same "issues" bolting to the beam web ? have your hanger wider than the beam flange, and fittings either end to attach to the web ...

Quando Omni Flunkus Moritati

 

[sbisteel]

There are some companies out there that make proprietary beam clamps that would work in this situation, Lindapter comes to mind.

They provide load tables for their products, which would eliminate any guess-work.

 

[JuniorCEng]

I was wondering what's the weight of the hanging object?
If the existing beam's flexrual capacity is enough to carry the additional load, i dont believe prying action would govern. the truss stability may need to be check though.

worst case, a gusset plate between the two flanges may solve the issue.

 

[BAretired]

I think it would be better to use a strap over the top flange and four threaded rod hangers down to the Tee section.

BA

 

[dylansdad]

Thanks for the responses so far. The load is maximum 250 lbs. This is in an existing manufacturing facility and no welding/punching is allowed. Thanks again.

 

[rb1957]

what's wrong with BA's idea ... straps over the top ? to be fancy, add a semi-circular block (so the straps don't kink)

"no punching" means you can't drill through the web ?

Quando Omni Flunkus Moritati

 

[msquared48]

Adjustable Beam Clamp

thread507-341734

Mike McCann
MMC Engineering

 

[dhengr]

dylansdad:
I would make the top clamp pl. as long as the WT is wide, and its thickness is to be analyzed and determined. Its width should be enough to match the WT length. To the inned edge, under side, of those clamp pls., I would weld a .25" thick x .5-.75" wide bearing bar, same length as clamp pl. To the outer edge, under side, of those clamp pls., I would weld another bearing bar, .5-.75" wide and thickness equal to (.25" + flange thick. of the B/C truss member), +/- a little probably o.k. The WT should be cut 4-5" longer than you show. Then, still put the bolts right near the flg. tips of the B/C truss member, as you show. You want that top clamp plate to design and act like a simple beam loaded near it mid point by the bolts, and you have defined the reaction points with the bearing bars. And, you load the bot. flg. of the B/C member favorably. Now design its thickness, vs. bolt clamping forces. Stay well below Fy, as you are designing a leaf spring. You have to check the truss and particularly the B/C member for these loads. That certainly looks like plenty of connection for 250 lbs. As for other states to check, I’d look into AZ. or CA.

 

[nac521]

For a 250# load, why not use a Unistrut beam clamp?

 

[spats]

B-Line has a whole series of different beam clamps for hanging pipes, and they provide good technical information, including CAD details.

 

[dvd]

That style clamp is used routinely in the conveyor industry. For a 250 lb load you are probably overdoing it. The 1/2" dia. c.r. bar should be ~1/16" larger in diameter than the flange thickness so that the toe of the 8x5 clamp bar is always in firm contact with the beam. I would analyze the 8x5 clamp bar to assure that it is thick enough that it won't lose contact at the toe of the bar, since losing contact at the toe could result in the beam clamp moving along the beam. I would also install the bolts with the head up so that the installer doesn't need so many hands. The 1/2" c.r. bar would better be h.r. in my opinion to avoid higher carbon c.r. bar being used. If you want extra safety run a loop of steel cable around the beam and through a hole on the hanging object and cable clamp it. Also, unless you have w14x68 laying around you may want to buy wt to avoid ripping the beam (could possibly use a weldment instead of tee section).