×
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

Tensile cracking limits in Class T post-tensioned beams

Tensile cracking limits in Class T post-tensioned beams

Tensile cracking limits in Class T post-tensioned beams

(OP)
I"m doing my first PT beam designs since the creation of Class T, and the increased limits on allowable tension. In going through the example in the ADAPT manual, they set the beam limits to 9 /f'c. I was going to use the full 12 /f'c, but now I'm wondering. Is there some reason to hold the limit to 9?

RE: Tensile cracking limits in Class T post-tensioned beams

I think the whole "class" system they introduced is a backward step.

Class T is a real worry. They say it is cracked. But there is no requirement for crack control or bonded reinforcement. For any design with stresses above class U and possibly from about half of the class U limit, there should be a requirement for minimum bonded reinforcement at the tension face and at a maximum of about 12 - 15" centres.

RE: Tensile cracking limits in Class T post-tensioned beams

Beyond class T, 12 sqrt(f'c), is class C which represents a cracked section. Class C sections do have to be detailed to control cracking. Allowing for classes is just a way to formalize the use of partial prestressing. An engineer, or client, is free to limit stresses to class U or T if they want the extra durability or improved appearance. Now there are more options.

RE: Tensile cracking limits in Class T post-tensioned beams

CooperDBM,

The "options" are simply meaningless limits. You can now put a name on something that is completely meaningless.

And they got the class T limit wrong. Bonded reinforcement is required to control cracking well below this limit!

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