Contact US

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!

*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

Minimum reinforcement ratio of thick concrete members

Minimum reinforcement ratio of thick concrete members

Minimum reinforcement ratio of thick concrete members

Hi there!
I need to design a thick concrete foundation of a tower crane. It needs to be 1.70 m thick to provide safety factor of overturning moments. Internal forces in the foundation section are not large, that's why even mimimum reinforcement ratio is overdesign. Is there any design rule for this situation? American or Europan codes are possible.

RE: Minimum reinforcement ratio of thick concrete members

You could maybe treat it as unreinforced and design it accordingly, although the rules probably vary a lot depending on what code you’re looking at.

But minimum reinforcement, even in such a thick section, should normally be a pretty small quantity. Considering the cost of pouring a 1.7 m thick footing, erecting by a crane, etc etc, the cost of the reinforcement would be pennies.

RE: Minimum reinforcement ratio of thick concrete members

Thank you for your comment. The crane supplier made a proposal for the foundation design and the reinforcements in this proposal are much less than the minimum reinforcement. if this is not based on a design code i will implement minimal reinforcement. The crane vendor cannot be reached. And pennies are calculated in the construction industry.

RE: Minimum reinforcement ratio of thick concrete members

Note that in ACI, minimum tension and shrinkage reinforcement is only calculated based on the top and bottom 12" (300mm) of the section. You can ignore the middle 1.1m. I'd want to say that in some cases, only the top really needs the T&S steel, but I'm not sure if that's in the code anywhere.

(This assumes that the section can be designed as unreinforced for flexure and shear internal forces).

just call me Lo.

RE: Minimum reinforcement ratio of thick concrete members

The ACI 318-14 minimum flexural reinforcement for foundations is as follows and is applied on each face (top and bottom) of the foundation mat.

RE: Minimum reinforcement ratio of thick concrete members

What's the downside if it cracks? How large is the foundation? 20'x20' or 200'x200'?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?


RE: Minimum reinforcement ratio of thick concrete members

You mentioned that “pennies are calculated in the construction industry.” Did you have experience with previous crane tower work where someone balked at the costs? It seems something as critical to the success of the project would be one of those expensive costs that all parties would be willing to live with.

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! Already a Member? Login


Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close