ASCE 7 Wind Loads C&C Help
ASCE 7 Wind Loads C&C Help
(OP)
I am currently calculating wind loads for an insulated metal panel assembly and had a few questions regarding the effective wind area. The IMPs are fastened (concealed fastening) at every girt/purlin location and every width of the panel and acts as one composite when installed.
In the Chapter 6 wind load commentaries of ASCE7, it states: "For a cladding panel, the effictive wind area may be equal to the total area of the panel. For a cladding fastener, the effctive wind area is the area of cladding secured by a single fastener."
Say I am using a 3' wide wall panel that is 30' long fastened to girts 5' o.c. Do I:
a) Take the effective wind area of the panel (30' x 3') to determine the wind load. Use that wind load and apply it to the tributary area of each fastening location to determine number of fasteners required at each location, or
b) Take the tributary area of each fastening location as my effective wind area to determine the wind load? If this is the case, there will be two different loads in the corner zone - one with a full tributary area and the edge panel with half the tributary area. Why would these areas see different loads if the wind is uniform and acting onto the full panel assembly as a whole?
c) Use the full panel length to calculated the effective wind area when determining whether the panel itself would fail (not fastening) or do I take the span length (girt to girt) to determine the effective wind area?
The code seems open to interpretation when it talks about the single fastener effective wind area and I am not sure which way to design the panels. Any insight would be great. Thanks and I appreciate the help.
In the Chapter 6 wind load commentaries of ASCE7, it states: "For a cladding panel, the effictive wind area may be equal to the total area of the panel. For a cladding fastener, the effctive wind area is the area of cladding secured by a single fastener."
Say I am using a 3' wide wall panel that is 30' long fastened to girts 5' o.c. Do I:
a) Take the effective wind area of the panel (30' x 3') to determine the wind load. Use that wind load and apply it to the tributary area of each fastening location to determine number of fasteners required at each location, or
b) Take the tributary area of each fastening location as my effective wind area to determine the wind load? If this is the case, there will be two different loads in the corner zone - one with a full tributary area and the edge panel with half the tributary area. Why would these areas see different loads if the wind is uniform and acting onto the full panel assembly as a whole?
c) Use the full panel length to calculated the effective wind area when determining whether the panel itself would fail (not fastening) or do I take the span length (girt to girt) to determine the effective wind area?
The code seems open to interpretation when it talks about the single fastener effective wind area and I am not sure which way to design the panels. Any insight would be great. Thanks and I appreciate the help.






RE: ASCE 7 Wind Loads C&C Help
Very simply, you use whatever tributary area corresponds to whatever you are analyzing: very small trib area for fastener; larger trib area for panel; larger still for whatever is supporting the panel.
RE: ASCE 7 Wind Loads C&C Help
Panel: Use span between girts. Multiple that times span/3 to get the effective wind area to determine cladding pressure. Use that pressure to design 1' strip of panel between girt supports.
RE: ASCE 7 Wind Loads C&C Help
The different pressures are based on probability of exceedance over the entire tributary area. So much more likely that a single fastener's pressure will exceed a given wind pressure than the whole panel's.
Don't think if it as 'different pressures' think of them as different safety factors or different probability of exceedance. So you have a base pressure (qh using ASCE 7-05) and then a coefficient to account for trib area, zone, etc. (GCp using ASCE 7-05). Everything's at the same pressure, the coefficient modifying the pressure just changes.
RE: ASCE 7 Wind Loads C&C Help
Concur with individual area for fastener area.
RE: ASCE 7 Wind Loads C&C Help
RE: ASCE 7 Wind Loads C&C Help
So, the effective wind area for the panel design is the (panel width x girt spacing). I'm still not too clear on the following: "For a cladding panel, the effective wind area may be equal to the total area of the panel." Is the code referring to single span conditions in this statement?
RE: ASCE 7 Wind Loads C&C Help
RE: ASCE 7 Wind Loads C&C Help
RE: ASCE 7 Wind Loads C&C Help
RE: ASCE 7 Wind Loads C&C Help