×
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

Roof Uplift

Roof Uplift

Roof Uplift

(OP)
With shallow roof pitches, windload on both the leeward and windward sides create an uplift.  Logically, this is hard for me to see.  How can wind hitting a surface actually lift it up?

I reason it as such... (correct me if I'm wrong)

It's similar to an airplane wing.  The air traveling over the top of it has to cover more distance in the same amount of time as the air under it.  The air above the wing is "thinner" (perhaps poor terminology), then the air under which creates the lift.  Same applies to a roof?

Is this even close?

Drew

RE: Roof Uplift

The vacume or suction on the leeward wall also generates suction.  The Normal Force Analysis Method, provides a more accurate description of the wind forces with inward and outward forces acting normal to all exterior surfaces simultaneously.

RE: Roof Uplift

When wind blows past an obstruction, the airflow separates from the obstruction at discontinuities.  A vacuum is formed at the discontinuities and suction pressure results.

As the air flows up and over the roof, it doesn't make a sharp turn and follow the roof pitch.  The separation between the airflow and the roof surface causes a vacuum (outward design pressure).  This also occurs at wall corners as the wind goes around the sides of the building.

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! Already a Member? Login


Resources

White Paper - A Guide to 3D Printing Materials
When it comes to using an FDM 3D printer effectively and efficiently, choosing the right material at the right time is essential. This 3D Printing Materials Guide will help give you and your team a basic understanding of some FDM 3D printing polymers and composites, their strengths and weaknesses, and when to use them. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close