ASCE 7-10, MWFRS Wall Loads on OPEN building?

[dbnerds]

This may seem like an oxymoron (wall wind loads on an open building), but sometimes this can occur.
I would like to understand which equations to use for elements and system using for MWFRS?
(btw, I'm using Directional - Part 1)

Section 27.4.3 "Open Buildings with ..." sounds like the right approach, but when I review equation (27.4-3) it appears to be aimed at ROOF pressures (due to the use of qh, not qz; & the CN coefficient appears to revolve around roof geometry exclusively)

Section 27.4.1 "Enclosed & Partially Enclosed.."'s equation of (27.4-1) seems like it would make more since once the internal pressure portions are omitted. However the NAME of the section doesn't seem to be supportive of this approach AND the table I would use to derive Cp (Figure 27.4-1) denotes "Enclosed, Partially Enclosed Buildings" (no love for Open structures?).

I've searched around the forum and seems like some designers using the minimum design wind loads (section 27.4.7) but that seems like a cheap way out.

Thanks,

 

[MrHershey]

I would tend to use free-standing wall loads. I don't know what table/section this is in ASCE 7-10, but was 6.5.14/Figure 6-20 in ASCE 7-05.

 

[ajh1]

ASCE 7-10 Section 27.4.3 indicates that for walls that could be deemed "fascia panels", which I take to mean partial height walls suspended from the roof plane as opposed to running from ground to eave, should be considered as an inverted parapet, i.e., use parapet loadings with forces on both the front and the back of each wall. (See Section 27.4.5)

 

[dbnerds]

Great feedback guys.

Mark, your method/model makes sense. However, I feel the thin/planar sign may not develop the same leeward forces as the depth of a full building.

ajh1, I like your method too. I like that its at least mentioned within the body of a section where this formula should be noted. I think its sad on ASCE's behalf that we have to "reason-out" this approach. much like the sign model, I'm not sure the planar volume of a parapet is quite like a building's? However, I think I'll run with this method. I think I'll tweak the formula for parapets a bit. Instead of using qp (at the TOP of the parapet), I'll evaluate the full height and figure the differing pressures using qh.

I'm writing an excel worksheet for winds of ASCE 7-10. think i'll compare the pressures derived from this varying height parapet method vs. the typical Enclosed formula (eq.27.4-2) while omitting the internal pressure portions (as i mentioned in the orig post). see what happens...?

not closing this post -- still open to feedback!