Beam end restraint
Beam end restraint
(OP)
Hello all,
I'm in a discussion with an engineer I work with about whether and where stiffeners are required for the assembly shown on the attached sketch. The W18 beams will be installed beneath badly deteriorating concrete beams to prevent collapse should the concrete beams fail. The top flange of the W18 is unsupported as there will be a gap between it and the concrete beams. The steel beams will be installed in discrete locations so there is no way to connect them together.
This engineer will seal the drawings and is responsible for the design, but I was assigned to review it. That we have this review process with no protocol to solve disagreements is one of the annyoing things about my company.
The disagreement here is that I believe some stiffeners are required to restrain rotation of the beam ends. The design engineer disagrees because he says that the W18 is compact, and the W14 bracket is not the same as a column that could become unstable.
I'm trying to decide how much of a fuss to make about this. What do you think? Is there any way that stiffeners are not required? If stiffeners are required, where would you put them? Should any stiffeners be added to the bottom of the W14 bracket?
I'm in a discussion with an engineer I work with about whether and where stiffeners are required for the assembly shown on the attached sketch. The W18 beams will be installed beneath badly deteriorating concrete beams to prevent collapse should the concrete beams fail. The top flange of the W18 is unsupported as there will be a gap between it and the concrete beams. The steel beams will be installed in discrete locations so there is no way to connect them together.
This engineer will seal the drawings and is responsible for the design, but I was assigned to review it. That we have this review process with no protocol to solve disagreements is one of the annyoing things about my company.
The disagreement here is that I believe some stiffeners are required to restrain rotation of the beam ends. The design engineer disagrees because he says that the W18 is compact, and the W14 bracket is not the same as a column that could become unstable.
I'm trying to decide how much of a fuss to make about this. What do you think? Is there any way that stiffeners are not required? If stiffeners are required, where would you put them? Should any stiffeners be added to the bottom of the W14 bracket?






RE: Beam end restraint
If you're looking for a reference to bolster your argument, look in the Steel Construction Manual, starting on page 10-84 in the 13th edition. There is also a paper referenced that might be helpful, "The Results of Experiments on Seated Beam Connections" by Roeder and Dailey.
RE: Beam end restraint
You may want to 'dry pack' the space between the beam and the concrete beam.
I would, normally, as a matter of practice use a stiffener myself.
Dik
RE: Beam end restraint
I woud refer to AISC 13th Edition Section J10.7 on unframed ends of beams and girders.
RE: Beam end restraint
Vertical stiffners would be another choice. I would do something here...not leave it as is that is for sure.
RE: Beam end restraint
RE: Beam end restraint
RE: Beam end restraint
A web stiffener would depend on the web buckling strength, a completely separate check that is usually not a problem except in short spans with high shears (in my experience).
Vertical stiffeners out-of-plane with the web could kill two birds with one stone, but I am guessing you only have one bird to kill. Murder that bird with a clip angle at the top of the beam.
RE: Beam end restraint
Did you mean "Murder that bird with a clip to the top of the skull"?
BA
RE: Beam end restraint
My understanding is that AISC requires ALL unframed beam ends to be stiffened because that is how the equations for lateral-torsion buckling are derived (how the ends of the beams are restrained during the tests that are used to develop the equations).
Most (nearly all) of the popular steel texts do not address connections with unframed unstiffened beams, even though it has to be done in practice all the time: although not necessarily by structural engineers, since they typically design only buildings and strictly to a code such as AISC. Just my 2 cents.
RE: Beam end restraint