ASCE 7-10 Wind loads on rooftop platform
ASCE 7-10 Wind loads on rooftop platform
(OP)
I am designing a platform to hold equipment on top of a building. I have already calculated my wind pressure. I am a bit confused on the force coefficient to use. I know to use Figure 29.5-1 for the force coefficient on the equipment, but unsure on what figure to use for the force coefficient on the platform itself. I am thinking I use the force coefficients in figure 29.5-2. The platform has four pipe columns, the beams are made out of wide flanges and channels and i have knee braces to stabilize the structure.
It would greatly appreciated any help on the correct way to calculate the wind force on the platform.
It would greatly appreciated any help on the correct way to calculate the wind force on the platform.






RE: ASCE 7-10 Wind loads on rooftop platform
It's possible that an uncommon geometry simply may not be covered by the standard. I suspect a platform above a building could have large uplift forces that aren't covered by the projected-area methods. Also note the section dealing with increased loading for rooftop equipment.
RE: ASCE 7-10 Wind loads on rooftop platform
Mike McCann, PE, SE (WA)
RE: ASCE 7-10 Wind loads on rooftop platform
Dik
RE: ASCE 7-10 Wind loads on rooftop platform
RE: ASCE 7-10 Wind loads on rooftop platform
RE: ASCE 7-10 Wind loads on rooftop platform
Yes, getting Cf from 29.5-2 (and loading each individual member for wind) would be one acceptable approach.
Also keep in mind that there is a uplift case to consider with rooftop equipment/framing.
Unquestionably. (Unless it runs hot/warm.....and even then I'm not sure you should ignore the ice load because you can always lose power in a ice storm.)
RE: ASCE 7-10 Wind loads on rooftop platform
RE: ASCE 7-10 Wind loads on rooftop platform
I didn't notice your height until after I posted. I think at that point, you can use Part 6 of Chapter 30 (C&C).
RE: ASCE 7-10 Wind loads on rooftop platform
RE: ASCE 7-10 Wind loads on rooftop platform
I think we are talking (then) more of a structure composed of flat surfaces. (I.e. then you would figure it by volume, ergo Eq. 10.4-2.)
To go back to the wind load for a second (while it is on my mind), I wanted to say: I went to a seminar on wind loading (based on ASCE 7-10) some years back and the guy giving it said that the wind load on rooftop structures with h ("reasonably") greater than 60' is just about what you get if you did it by that section anyway. At the time, I don't think they had the research to justify it in excess of that. Not sure if that has changed since. (I know that is not much of a source.....but I thought I'd mention it anyway.)
RE: ASCE 7-10 Wind loads on rooftop platform
So basically there just isn't enough research on rooftop equipment above 60ft get mentioned in asce 7-10. Just to double check, the uplift acts simultaneously with lateral wind force on the equipment?
RE: ASCE 7-10 Wind loads on rooftop platform
RE: ASCE 7-10 Wind loads on rooftop platform
That's what I've typically done. (In the proper combination with minimal Dead Load.)
Most definitely.