Cantilevered Beam to Support Roof Guardrail System 2

[EV11]

I am analyzing the attached detail. It is a cantilevered beam that is supporting the guide rail system for the roof of a structural steel building. As you can see, the cantilevered beam is connected to a perimeter beam of the building. This perimeter beam runs parallel to the open web steel joists and therefore isn’t supporting much roof load.

To withstand the moment applied at the cantilever beam to perimeter beam connection, I was thinking of welding the top and the bottom of the cantilever beam flanges to the web of the perimeter beam.
One thing I am concerned about is the web of the perimeter beam. I will check to make sure that the beam is able to resist the applied weak-axis moment, but are there other factors I should be considering when analyzing the web of the beam? I’ve also added a stiffener to help strengthen the web.

Any other feedback or suggestions for the detail would be appreciated.

Thank you.

 

[SRCELL]

This detail puts torsion into the perimeter beam and does not resolve it.

 

[human909]

SRCELL puts it succinctly.

Unless there is another load path we are not seeing those guard rails will have excessive deflection and be fairly ineffective. The moment they can apply to that W310x28 could cause damage to fixings and other parts of the structure.

 

[AK4S]

Agree with SRCELL. This detail puts torsion into the perimeter W310 beam, so you need to either ensure the beam can take this torsion without excessive rotation or find a means to restrict torsion in the beam.

 

[EV11]

Thank you for your feedback. I will verify whether the W310 beam can take the applied torsion.

AK4S – do you have any suggestions for a means to restrict torsion in this situation?

 

[JLNJ]

Unless the W310 is torsionally fixed at its ends (or at other points) it can't "take" any torsion. The system is fundamentally flawed.

 

[phamENG]

Kick a brace up to the diaphragm. But your weak point in the load path is bending of the flange of the little intermediate beam you have in there. Sure, it'll take a lot to fold that over, but you've got a pretty nice moment arm there to make it happen.

 

[TLHS]

You can resolve the torsion if you moment connect kicker beams occasionally (for a very small load) to your main beam and then pin connect them to the joist running parallel or a channel you add a few feet away from the beam.