Rectangular HSS Beam-- Fixed Support

[steelbeam]

I have a 14 x 4 x 3/8 HSS beam that carries torsion to the end supports and I have been unable to find an example for the design. I am thinking of a stiffener plate on each side of the
section welded to the bearing plate and face of the tube with the overturning forces (couple) taken into the anchor bolts and into the concrete support. The other thought is to use holdown
clip angles, the same idea as used in building columns. I am wondering if someone out there has been there done that or can direct me to an example. I can't find anything in my textbooks.

Thank you for any help you can give me.

 

[rb1957]

you're thinking of an endplate to finish the I-beam and to provide a nice, sensible, area to join the two beams together with 4 bolts thru ? and the 4 bolts would carry the torque and the support (shear) reaction.

there are of course other ways (to skin this cat) but your's sounds ok to me.

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

 

[KootK]

Are you dealing with torsion and strong axis moment at the beam support?

Is this an HSS tying into a concrete wall? Side of wall? End of wall?

Big or small moments/torques?

Does the wall exist or is it part of the new construction?

Can tolerances be accommodated at the other end of the beam or do they need to be accommodated at this connection?

How sensitive will your structure be to twisting of the HSS?

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[BAretired]

Not sure I get the picture. A sketch might help. Stiffener plates welded to the face of HSS may be too flexible because the HSS wall will bend. End plates would work in theory but may not be suitable for erection.

BA

 

[kc9508]

Can you just allow the HSS section to "twist" - i.e. assume the end supports are pinned? It may greatly simplify the design. HSS sections generally twist very little under torsional loads, so the surrounding structure may not be that sensitive to it. Just a thought.

 

[steelbeam]

I would like to clarify my description of original question regarding the design of support for torsion of the HSS section. The HSS is a simply supported beam, no moment about the major axis at the supports. There is torsion (16 ft.-k)about the longitudinal Z-axis which must be resisted. The beam ends will have bearing plates bolted to the top of existing concrete walls. I am thinking that stiffener plates shop welded on each vertical face (14" height of HSS) that would look the same as end bearing stiffeners on a wide flange or plate girder would help resist the torsion in addition the HSS.
Before I try to wing it I was asking if anyone has a design example of this analysis/design. I have searched my text books and AISC to no avail.

Thanks for any help you can provide.

 

[KootK]

It's an excellent idea for stiffening up the connection with respect to twist, especially if the plate can be a bit wider than the HSS. I don't know of an example, unfortunately, but this is how I would approach it:

1) split your torsion up into a top and bottom face force couple. Size welds and apply them all around for good measure.

2) apply the top face load determined above to the top of the end plate as a load in a cantilevered plate and design through to the concrete accordingly.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[KootK]

Blodgett might have an example of something like this. I don't know of one per se but it seems like the kind of thing that he typically covers.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[BAretired]

If x is the distance between anchors, consider a tension of Mt/x on one anchor and a compression of Mt/x on the other. Design the base plate to resist the calculated bending moment. Provide a 3/8" end plate fitted into the HSS for closure.

BA

 

[steelbeam]

KootK, I have looked at Blodgett's text. I have a first printing that I purchased while in college and thought I may try use one of his examples for moment at the base of a column if I couldn't
find anything closer to my situation. Back then he had nothing covering HSS sections.
Thanks