Canopy Design
Canopy Design
(OP)
I need to design a steel canopy with concrete columns. It will be a proximately 25'x40'. I have never done this design, however I am very familiar with uplift, wind loads and so forth. My question is the follwoing: Is there a manual or design guideline for these type of structures?






RE: Canopy Design
They are designed as open structures, usually with monoslope roofs.
RE: Canopy Design
RE: Canopy Design
1.Layout the canopy column and roof framing plan.
2.Study your applicable code. Various codes have certain requirements for the canopy. Florida Building code for example, has entire section dedicated to canopies. You need to determine if it is temporary or permanent type canopy.
3.Determine the canopy roof loads to include deal, live, wind and seismic as applicable.
4.Design canopy roof members for gravity (DL, LL, WL and SL).
5.Design canopy for lateral stability. You may consider vertical bracing or moment connections.
6.design foundations and provide adequate uplift safety factor (not less that 1.5)
If you are not an engineer, I strongly recommend that you seek one who is licensed in your area. If you are and engineer in training, you may want a senior engineer to review your design.
Regards,
Lutfi
RE: Canopy Design
GlobalPEC
RE: Canopy Design
Also, if you are using ASCE 7-02, and you use Figure 6-18, be sure to check both the distributed condition and the load application point as noted in the figure notes.
If you are not using a fixed base condition, you'll probably need knee braces or at least gussets at the column-beam connection.
RE: Canopy Design
My canopy will have two columns and it will be used for a clinic entrance...Its for show
I read the IBC yesterday and found out that I need to design for a 20psf live load but I could not find anything about the uplift. Is it 125psf for open strcutures? seems high!!
The columsn will be fixed on the base. I have not decided whether they will be concrete or steel yet.
RE: Canopy Design
www.dittdeck.com
Yes, 125 psf sounds quite high. Generally, you are looking at somewhere between 25 and 40 psf for uplift, even in relatively high wind areas.
20 psf is typical for the live load, but check the rain load depending on the type of roof/deck you will have. It can sometimes exceed the typical live load if you have damming or if your deck profile is deep.
RE: Canopy Design
Have you seen steel rods used to help with the uplift loading? I was thinking about using a 1" or 2" in diameter steel rods rather than cables, what do you think?
Thank you...GlobalPEC
RE: Canopy Design
I did one about two weeks ago with double stainless steel cables (top cable to handle DL+LL...bottom cable to handle wind load) and turnbuckles.
Occasionally I've had an Architect refuse to budge on the "rod" issue....they wanted a certain profile and were not concerned about the structural aspects. In those cases, I had to design the deck to cantiliver with a moment connection in the deck plane, and using the rod only as supplementary support. That will only work if you have a cast-in-place concrete wall or a steel framed building....it won't work on masonry because the anchorage loads are too high. It throws a hellacious moment into the wall or soffit beam (torsion).
I'm not sure you can reasonably design an open structure canopy for tornadic winds. Large sail area...small connections.
RE: Canopy Design
If you have to design for a tornado, you'll have to read FEMA 361...and your design pressures will be astronomical 150 - 250psf, and that's only good for a Category 1 or 2 tornado. You cant design for any higher.
RE: Canopy Design
I deal with a lot of open structures which have gable and hip roofs. Do you use the force coefficients for a monoslope roof?
RE: Canopy Design
RE: Canopy Design
Thank you all for your help
RE: Canopy Design
Correct me if I am wrong, my understanding is that the wind loads for partially enclosed strutures are higher than enclosed or open structures.
For the open stuctures I deal with, such as pinic shelters, the use of a higher conservative load, can really impact the cost of the structure.
I suppose what I really need to do is post a question about open structures on the wind forum.
RE: Canopy Design
RE: Canopy Design
RE: Canopy Design
RE: Canopy Design
For everyone else, thank you very much for all your input and carrying the conversation with me.
GlobalPEC
RE: Canopy Design
RE: Canopy Design
Thank you for the information. I will have to order the 2005 ASCE-7