Vibrations on Roof Deck

[Nulukkizdin]

Was curious if anyone has ever looked into vibrations for metal deck on steel wide flange framing with no concrete topping. Looking at DG11, I understand that their fundamental assumptions are made based on a concrete on metal deck floor system on steel beams or joists. Similarly I understand that it would be best practice to go with concrete on metal deck on top of steel beams. That said, I am just curious if there is a way to evaluate vibration criteria(regardless of it's a good idea or not) for a system lacking the concrete topping and if anyone has looked into it before.

 

[Agent666]

Just use the same general provisions, they aren't tied to a particular construction type. It's all about mass and stiffness and damping. Less mass but less stiffness also, probably less damping also. Need to work through the numbers to see how this affects your particular scenario.

Anecdotally if I were to guess I'd say you'd have a hard time hitting any reasonable acceleration limits as the mass is significantly lower without the concrete, much lower than the ratio of change in stiffness.

 

[WARose]

What sort of vibration issue are you anticipating? Excitation from human traffic? If that is the case, some of the same charts in DG 11 that deal with human perception are applicable here as well.

But in any case, for a roof, I wouldn't think human traffic would be frequent enough to warrant such a investigation. (Your roof could be different though.) I'd just observe deflection limits and let it go at that.