×
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

Longitudinal rebar for long & narrow (high aspect ratio) SOG

Longitudinal rebar for long & narrow (high aspect ratio) SOG

Longitudinal rebar for long & narrow (high aspect ratio) SOG

(OP)
We are assisting a local concrete/aggregate manufacturer with replacement of a 40 year old truck scale (pit type) with a new type - that 'sits' on a slab at four bearing/support points for each of multiple weigh-scale beam 'spans'. The truck scale is located under overhead aggregate storage bins.

The old scale has 8" RC perimeter walls about 9' apart, and the pit was about 5 ft deep. The 'pit' is being backfilled and will be topped with a new 12" thick RC slab.

Total length of new slab is more than 200 ft, with a width of 10'.

The scale manufacturer has a 'canned' slab design - thickness, rebar, etc, and a minimum bearing capacity requirement for any compacted backfill etc.

The new slab will be engaged into the existing perimeter scale walls, and this will provide significant restraint to shrinkage in the longitudinal direction. Coupled with such a high-aspect ratio of >20 and this is destined to crack, IMO.

So I was expecting to see a bunch of rebar in the long direction - but the 'canned' design has the equivalent of 0.13% rebar in the long direction. No joints detailed that I am aware of.



Expected service life is probably 15+ years.

Anyone venture a 'guess' on expected crack width and spacing?




RE: Longitudinal rebar for long & narrow (high aspect ratio) SOG

2 mm wide cracks at 3 metre spacing.

RE: Longitudinal rebar for long & narrow (high aspect ratio) SOG

...and further to Hokie... at random locations and not straight... could wobble by a couple of inches either way. Can you not sawcut it in 10' panels... look a lot nicer.

You also have to sawcut it at the right time, too.


Dik

RE: Longitudinal rebar for long & narrow (high aspect ratio) SOG

My money's on the engagement of the existing walls dominating things here. Relatively small, distributed cracks.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: Longitudinal rebar for long & narrow (high aspect ratio) SOG

Can you introduce slab expansion joints along the 200 ft. length? Would the scale equipment allow that?

Check out Eng-Tips Forum's Policies here:
FAQ731-376: Eng-Tips.com Forum Policies

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