×
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

PTI's 2004 Post Tension Design Values for soil seem high?

PTI's 2004 Post Tension Design Values for soil seem high?

PTI's 2004 Post Tension Design Values for soil seem high?

(OP)
I've been using the Post-Tensioning Institute's new 2004 3rd ed. Design Manual (AKA Alternative Procedures).  I'm finding the soil design values I'm getting are significantly higher than the previous methods   

For example, a structural recently told me he calced a small, one-story, rectangular, residential home with a 20" P-T slab with tendons at 12" on center, in central AZ.  Obviously, this sounds like way too much slab.  The soil is a CH with LL=63, PL=23, clay=45% of total fines.  Em center/edge = 6.7'/3.5' and ym swell/shrink = 2.85"/1.14".  

I'm looking for some other people's experiences with the new design methods.  Thanks for any comments.

RE: PTI's 2004 Post Tension Design Values for soil seem high?

Glad to here you are using the new porcedures. I think there has been a great deal of misinformation and misunderstanding going around Arizona regarding the new procedures, both structural and geotechnical. One issue is that there seems to be incorrect assumption that the structural equations have not changed. This is incorrect, and using soil parameters developed using the 3rd edition procedures with the 2nd edition structural equations can result in overly conservative slabs. The Ym values you listed are big numbers and don't seem typical for Arizona. What part of the state is this in?
--Jim

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