×
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

Waffle slab parking deck with overhang

Waffle slab parking deck with overhang

Waffle slab parking deck with overhang

(OP)
I've been asked to calculate the allowable load on the overhang portion of a waffle slab parking deck.  How do I treat this case?  The L/s for the overhang section is < 2 so it normally would be treated as a one-way slab but the joists make it so it deflects as a two-slab.

Thank you in advance.  I hope I've explained my problem clearly.

RE: Waffle slab parking deck with overhang

(OP)
Correction to my original post:  L/S > 2 (30'/9')

RE: Waffle slab parking deck with overhang

I have done this calculation before but can't find a book that directly indicates its OK to do so for a cantilever. Here goes. Based on your dome data, void volume and top slab thickness their is an "average equivalent slab thickness". You have to compare both the transformed sections and equate each of the moments of inertia. You must get the 1980 or 2002 CRSI Manuals to review their calculations procedures and adjust it to your overhang condition. Hope this points you in the right direction. Good Luck.

RE: Waffle slab parking deck with overhang

I think the joists are not rigid enough to act as supports.so the slab doesnt treet as a one-way slab.so you shoud distribute the loads based on the stiffness of slab and joists.I can suggest you using SAFE or ETABS2000.

RE: Waffle slab parking deck with overhang

leighcheri,

If by overhang you mean cantilever, the L/s > 2 rule would not apply anyway. This is for normal spans supported on 4 sides.

With a 9' cantilever and a 30' span, it will be 2way.

Do not forget to calculate real deflections if you are using safe or etabs or any other FEM package, allowing for cracking and long term effects.

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