×
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

Pan Joist question

Pan Joist question

Pan Joist question

(OP)
Section 8.11.4 of ACI 318-99 says, "joist construction not meeting the limitations of [monolithic construction and certain rib width, depth, & spacing limitations] shall be designed as slabs and beams.  What exactly are the differences between the design of slabs & beams vs. joists?  I see in section 8.11.8 that you get a 10% bonus in shear strength for joists but, I am not aware of any other differences.

RE: Pan Joist question

That is one difference (8.11.8)

Also, for joists, you can use 3/4" clearance instead of 1 1/2" (See Chapter 7 - section 7.7.1(c)).  And joists get another break with minimum shear reinforcing (see 11.5.5.1(b))

References are from ACI 318-02.

RE: Pan Joist question

(OP)
Thanks JAE.  Gosh, wouldn't it be nice if the index of ACI 318 under "joists" actually referenced those sections that involved joists???  

Wonder why with wood design you get a 15% bonus in flexural strength for repetitive members but nothing for shear.  And in concrete design you get a 10% bonus in shear strength for repetitive members but nothing for flexure?

RE: Pan Joist question

Perhaps:  Wood is much more resilient in flexure (can take higher short term loads without failing), and the wood shear is a very high variable....

And for concrete, the ability to engage multiple joists at one time and spread out flexural moments is more difficult due to the high rigidity of concrete....and for shear... I dunno.

Or its just how the codes morphed and evolved politically....who knows...

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