component and cladding wind load for balcony

[smokiibear]

What is used for vertical wind loads for components and cladding on balcony's and decks? Flat roof overhang for upward and Roof for downward?

 

[lexpatrie]

Download from wind is an interesting question but I don't think ASCE is there yet, perhaps 2026. The download is more typically based on the occupancy served so 40 psf or 60 psf (1.5x occupancy served) or 100 psf it it's like a fire escape or egress path deck. You could perhaps look at it as an open structure for the wind uplift loads, but I'm not convinced a lot of designers consider that, not that it isn't appropriate, it's just I don't see a lot of designers being quite that rigorous.

 

[HTURKAK]

A sketch will be helpful to understand your problem. Your approach , flat roof coefficients for upward and downward direction could be one of the reasonable approaches specially If the question is for cladding underside the balcony deck. Another approach could be roof overhang approach. Pls look also 30.12.5 for underside wind loads .




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[milkshakelake]

I use monoslope free roof with roof angle 0 from ASCE 7-10 for both upward and downward loads. If it ain't broke, use it.

 

[jjl317]

Depending on the orientation of these components, the ASCE 7-16 criteria for canopies which might be appropriate.

 

[smokiibear]

Speaking of Canopies, what is guiding principal of weather to use the Figure for "Pressure Coefficients on Separate Surfaces of Attached Canopies" vs "Net Pressure Coefficients on Attached Canopies Considering Simultaneous Contributions from Upper and Lower Surface"

Furthermore, in ASCE 07-16, Figure 30.11-1A, why do they list hc & he?

Are upper surface and lower surface added together for upward and downward?

In the end, I suppose it would be safe to take the critical load from CC (monoslope enclosed, monoslope open, canopy or MWFRS). Not ideal, but comprehensive.

Last thoughts?

 

[hokie66]

In the direction parallel to the edge, free roof pressures are applicable. But perpendicular the building, I think the pressures on the balcony are equivalent to pressures on the adjacent wall.

 

[BulbTheBuilder]

ASCE 7-22 has more information on the canopy wind load

what is guiding principal of weather to use the Figure for "Pressure Coefficients on Separate Surfaces of Attached Canopies" vs "Net Pressure Coefficients on Attached Canopies Considering Simultaneous Contributions from Upper and Lower Surface"

" Pressure coefficients on separate surfaces of attached canopies on buildings" are used to design fasteners of the top and soffit elements that's why you have coefficients for both faces. Ref ASCE 7-22 Comm. C30.9

"Net pressure coefficients considering simultaneous contributions from upper and lower surfaces on attached canopies on buildings" are used to design the structure of the canopy (girder, joist, post)Ref ASCE 7-22 Comm. C30.9.
It is also for canopies with only one physical surface.

why do they list hc & he?

I think this is to account for differences in the canopy and roof elevation when you refer to the "Net pressure coefficients considering simultaneous contributions from upper and lower surfaces on attached canopies on buildings". The height of the canopy relative to the roof affects your wind pressures (both +ve and -ve) as qh is used to compute the pressure

Are upper surface and lower surface added together for upward and downward?

If you're using figure 30.11-1A from ASCE 7-16, no. it is already combined in figure 30.11-1B Net pressure coefficients considering simultaneous contributions from upper and lower surfaces on attached canopies on buildings.