×
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

Allowable Reinforcing Steel Stress Increases
3

Allowable Reinforcing Steel Stress Increases

Allowable Reinforcing Steel Stress Increases

(OP)
In designing a concrete grade beam resisting live and dead loads as well as wind/seismic OTM...can I take any stress increases for the reinforcing steel? Codes are ACI 318, 2006 IBC. Thank you.

RE: Allowable Reinforcing Steel Stress Increases

In ultimate strength design, there are not "stress increases."  The various load combinations accomplish what you are looking for.

DaveAtkins

RE: Allowable Reinforcing Steel Stress Increases

Dave is correct.  In concrete you are dealing with strengths, not stresses.  The only time you can consider a stress increase is using ASD, you can't when using LRFD.  Additionally, IBC doesn't allow the use of the 1/3 stress increase unless you use the "alternate" load combinations (which essentially increase certain load cases by roughly 1/3).

RE: Allowable Reinforcing Steel Stress Increases

(OP)
DaveAtkins and StructuralEIT. Thank you both for answering my question. In California we are still sorting out the ICC, and as an architect I am less familiar with concrete strength design as I am with ASD wood design. Haven't tried LRFD for wood yet.  

RE: Allowable Reinforcing Steel Stress Increases

Are you designing concrete using ASD?  I don't believe ACI 318-05 even recognizes ASD.
Either way, you can only use the 1/3 increase if the following two conditions exist:
1.  You use the alternate load combinations out of IBC for ASD.
2.  The material specification specifically permits its use.

RE: Allowable Reinforcing Steel Stress Increases

ACI 318 does recognize ASD - just in a very indirect way - see chapter 1, commentary section R1.1 - 5th paragraph.

 

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