×
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

Designing a concrete girder with a top and bottom flange

Designing a concrete girder with a top and bottom flange

Designing a concrete girder with a top and bottom flange

(OP)
What value of b (width of beam) would I take if my concrete girder has a small flange top and bottom in the calculation of flexural resistance? I am curious what normal practice is. Also, how would shear reinforcement look for a girder of this shape? Much thanks.

RE: Designing a concrete girder with a top and bottom flange

Depends on whether the top or bottom is in compression and the amount of reinforcement.  The depth of compression block, a, is set by how deep it has to be for 0.85f'c to balance out Asfy on the tension side.  If this isn't deeper than the flange thickness, then use the compression flange width.  If it's deeper than the flange, then you'll hvae a T-shaped compression area.  If the bottom is in compression, it's the same situation except upside-down.  

Find a T-beam example in a concrete textbook and you'll see exactly how to do this.  The tension-side b won't come into play for flexural calcs.

Stirrups depend on the proportions.  Almost certainly will have a typical looking stirrup in the web, but might also have a rectangle enclosing the bottom flange.

RE: Designing a concrete girder with a top and bottom flange

just to add to what 271828 said, the most common reason for having a bottom flange would be to fit more steel in there.  Unless you are getting negative moments, that extra concrete at the bottom flange is irrelevant.
Consider prestressed concrete bridge girders with an I shape.  They are only shaped that way to allow more prestressing strands at the bottom of the section.

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