×
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

Pre-cast Retaining Wall - Mass Concrete Base Design

Pre-cast Retaining Wall - Mass Concrete Base Design

Pre-cast Retaining Wall - Mass Concrete Base Design

(OP)
Hi all,

We've been tasked with the design of retaining structures utilising precast 'L-shaped' wall element.

Ordinarily I would specify the pre-cast elements to be dowelled in to an RC base designed to resist the overturning moments and sliding.

In this instance we have been asked to prepare a mass concrete base option for these structures.

My initial thoughts were the following.

-
The pre-cast wall is dowelled in to the mass concrete
-
The overturning from the precast panel is resolved in to a tension force within the dowels in to the mass concrete
-
Sliding is resisted through shear transfer of the dowels
-
The resulting OM from the vertical and horizontal forces are resisted by the weight of the mass concrete foundation to achieve appropriate FOS
-
The sliding is resisted by base friction and passive resistance of the soils to achieve appropriate FOS

I'd be grateful for any thoughts on the above.

Thanks

Neil

RE: Pre-cast Retaining Wall - Mass Concrete Base Design

Dont assume full passive resistance for sliding... ignore it or at least give a good factor of safety...

RE: Pre-cast Retaining Wall - Mass Concrete Base Design

(OP)
Thanks EireChch,

Other than that does that approach seem reasonable?

Thanks

Neil

RE: Pre-cast Retaining Wall - Mass Concrete Base Design

If you need tension ties at the back of the precast to prevent overturning then there will be significant bending moments in the base so it should be reinforced, not mass concrete.

Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/

RE: Pre-cast Retaining Wall - Mass Concrete Base Design

I have designed reinforced concrete retaining walls, but not precast walls dowled into an RC base. I will have a go regardless and some of the structys can correct me. Note, my opinion is based on my gut feel and nothing more...

-
The pre-cast wall is dowelled in to the mass concrete
-
The overturning from the precast panel is resolved in to a tension force within the dowels in to the mass concrete - I doubt practically you will get enough capacity in the dowels. Typically in an RC wall you have L bars that are lapped up the face and then returned back into the base. This is a good connection in my mind. But a number of dowels to resist overturning?? Not sure...May you can put enough deep dowels, at large diameter at close spacing but will this be practical. Also, is the overturning moment resolved into a tension force? I would think some portion of it will be but not a good chunk wont.
-
Sliding is resisted through shear transfer of the dowels - sliding will be resisted by the base friction as you have said below. The pre cast panel will receive some shear force at the connection which will be transferred to the dowels. I think that should be easily achieved.
-
The resulting OM from the vertical and horizontal forces are resisted by the weight of the mass concrete foundation to achieve appropriate FOS. The weight of the wall (stem and base) will resist overturning, but again will it be practical to rely on increasing the thickness of the the members to get the FOS. Increasing the heel length will give you more bang for your buck with the additional soil weight.
-
The sliding is resisted by base friction and passive resistance of the soils to achieve appropriate FOS

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


Resources


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