×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

ASCE 7-05 Canopy Pressures

ASCE 7-05 Canopy Pressures

ASCE 7-05 Canopy Pressures

(OP)
I have a 9 ft deep canopy and am trying to figure out what wind pressures are appropriate for the face of the canopy. I can get the roof pressures easily using the tables. And typically I have been using those roof pressures and calculating the pressure on the face assuming it to act as a solid sign above ground. Resently I have been thinking that might not be totally right. Shouldn't there be some windward and leeward pressures on the front and back faces? Any thoughts?    

RE: ASCE 7-05 Canopy Pressures

I agree with you that the force coefficients for solid signs might not be the best approach.  If you read the commentary to Fig. 6-20 of ASCE7-05, you find that these force coefficients were derived using wind tunnel tests on solid signs and free-standing walls that, presumably, are very thin in the plane of the wind load.

What is the configuration of your canopy (gabled? flat? troughed?)  If it is flat, I would probably use components and cladding wall pressure coefficients evaulated at the highest point of the canopy.   

RE: ASCE 7-05 Canopy Pressures

(OP)
It's flat. What steered me away from that was the tables say that the coefficients are for enclosed or partially enclosed. It seems you could use the external pressure coefficients and not the internal to get what I'm looking for.  Thanks.    

RE: ASCE 7-05 Canopy Pressures

Be careful. Canopies seem to be the first thing to fly away in a strong storm, leading me to believe that we don't have a handle on the design pressures.

The British and Canadians have some info in their codes which might be a helpful addition to ASCE 7.
 

RE: ASCE 7-05 Canopy Pressures

I'm also designing a canopy with similar conditions.  Mine has a flat roof with soffit panels underneath.  The fascia is vertical with a height of 3 feet.  For vertical wind loads, I used ASCE 7-05, Figure 6-18A, with a slope of 0 degrees.  For horizontal wind, I used Figure 6-20, Cases A and B only.  I decided that Case C was unique to signs because of the aerodynamics of flow around a flat plate.  I decided to use Figure 6-20 instead of assuming this was a fully enclosed building because of the height to length ratio (the canopy dimensions are 40'x45').  I decided that this situation could be evaluated similar to the simplified method where you use just the projected area of the structure versus calculating the positive and negative pressures on the windward and leeward sides.

RE: ASCE 7-05 Canopy Pressures

See ASCE 7-05 section 6.5.13.2. Open buildings with flat roofs should use parapet wind pressures on the fascia for MWFRS calcs.

RE: ASCE 7-05 Canopy Pressures

(OP)
Perfect. Never read that before. Thanks.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources