Open Structure

[JedClampett]

In Section 1603.1.4 of the 2006 IBC, you're required to illustrate component and cladding loads on the design documents. I do this by showing a roof plan, dividing the roof into zones corresponding to ASCE 7 (1, 2 and 3) and showing a small perspective view of the building to show zones 4 and 5. I then give a table of the wind pressures vs. the effective wind areas in each direction.
Does anyone have any tips on how to show component and cladding pressures on an open structure (ASCE 7-05, Figure 6-20)? There's no zones, there's no EWA and there's really only one load direction.

 

[woodman88]

Illustrate? My IBC Section 1603.1.4 number 5 states “Components and cladding. The design wind pressure in terms of psf to be used for design of exterior components and cladding materials not specifically designed by the registered design professional.”
For this I have always calculated the maximum value and shown it as “C&C wind load = XX psf” in the GSN. If anybody needs to use a lesser value they can contact me or calculate that location C&C themselves.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

 

[JedClampett]

This is a Florida Design with 146 mph wind speed. We usually give an illustration defining zones, EWA, etc. The table is actually pretty involved. I've seen it done this way and pertty much copied it. I'm guessing it's done that way because the louver, door and window suppliers charge a premium for the corner design values.

 

[ron9876]

Jed why not the zones for C&C in Figs. 6-19?

 

[JedClampett]

Figure 6-20 doesn't have zones. There are three cases. Case C does have a load that varies depending on the distance from the edge (or corner). If no one has any suggestions, I'll just use that and call the portion closest to the edge, zone 5.

 

[ron9876]

But Fig. 6-19 has zones for C&C loads for open buildings.

 

[JedClampett]

6-19 is for a roof with no walls. I have walls with no roof.

 

[UcfSE]

I would just put the design pressure on the plans as a statement instead of the usual diagram, perhaps at the end of the other wind loading criteria. I do that with other structures such as exterior exposed stairs and parapets. There is no diagram as you've noticed, so it doesn't really make sense to invent one.

 

[woodman88]

ASCE 0 05 section 6.5.12.4.3 states that fig 6-11 to 6-17 and fig 6-5 shall be used for the design values of parapets C&C. And without a roof all you have is either walls or parapet walls. From fig 6-5, I would go with the enclosed building values, not the open building as I see the “building” would be the floor and down and the walls above as the parapets.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

 

[ATSE]

Nothing communicates forces better than a graphic load diagram. Not just for wind, but for retaining walls and metal building column reactions, and anything else where engineers can come to different answers using different code interpretations or governing load combos.
That's one of the reasons drawings ("plans") are superior to book specs - book specs don't have figures.
Jed, I suggest 2-D figures of your wall with load arrows - one looking from the side, and one looking down.