canopy design

huangyhg

canopy design
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?
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not aware of any design manual for canopies.  i've designed hundreds of them.  
they are designed as open structures, usually with monoslope roofs.
thank you ron for your input.
i would recommend the following steps and these are not all inclusive of every step:
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.
thank you very much lutfi...i am trying to get as many inputs as possible prior to starting the design on monday morning.
globalpec
globalpec...good info from lutfi.  would add that you not forget to consider the lateral load on the faces of   
thank you ron.
my canopy will have two columns and it will be used for a clinic entrance...its for show .  i was thinking about designning it as a cable stayed brigde with cantilever   
not sure where you are located, but this is a common canopy application.  check out some of the manufacturers who supply these in aluminum...
thank you ron...i am in oklahoma and i need to worry about high winds due to tornadoes.  no worries about rain loading, it should not collect any water.
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
globalpec...rods don't work well with uplift as they will be in compression and buckling is an issue (unless you're talking about tension rods from the bottom).  i've designed lots of "hanging" canopies that have cantilevered decks with a hanger "rod" supporting the deck, angled from the wall.  for these, we usually use a 2 or 3-inch diameter schedule 10 aluminum pipe, attached through a clevis device.
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.
does the owner ask for the design be made to withstand a tornado?  that's unlikely.  the wind design should be based upon asce7....for oklahoma is 90mph 3 second gust wind speed.  the wind pressures vary between structure type, height, and location.  its not as easy as, design it for ""psf.  this is engineering, not mcdonalds
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.