Sharp Corners in CIP Retaining Walls 3

[donaldjr87]

I cannot find anything in ACI-318 or 350 that addresses the additional reinforcement requirements at a corner in a retaining wall, unless I overlooked it. I know it is common practice to put additional horizontal bent bars or hairpins at the corners. Is there anywhere in the code that addresses this.

By the way, I am dealing with cantilever retaining walls that hold back soil and also tank walls.

Thanks for your help,
Donald

 

[Teguci]

You could detail it to allow the elements to act separately. Pretty sure ACI 14.2.6 doesn't apply unless you have a column coming down in the corner. My preference is to lock the two together. Just make sure you have a control joint at half the maximum spacing from the intersection. Also, if you are using the walls as grade beams, there will be additional torsional resistance from the interlocking walls which will require a lot more reinforcement (partially fixed instead of the assumed pin).

 

[dcarr82775]

Calculate the horizontal moment and size the steel accordingly

 

[JAE]

Is the corner a re-entrant corner where the earth pressure is attempting to separate or tear apart the corner?

Or is it an external corner where the loads are pushing the orthogonal walls together?

In either case, dcarr is correct to analyze the wall's horizontal moments and design accordingly. In the case of the re-entrant corner, you also have to look at shear-friction through the wall and provide tensile rebar as well.

 

[donaldjr87]

The corner is a re-entrant corner but you guys answered my question. Thanks.

 

[hokie66]

If the wall is designed as a cantilever, I think the normal practice of continuing the horizontal reinforcement with hooked bars extending to the opposite side of the wall works fine. If the wall spans horizontally and there is an "opening" corner, hairpin bars are required if the joint is to be efficient. There have been a few threads on this issue in the recent past.

 

[slickdeals]

A very good article on detailing corner reinforcing is attached. Also the efficiency of different reinforcing bar details for moment capacities based on testing is provided at the end of the article.

It’s no trick to get the answers when you have all the data. The trick is to get the answers when you only have half the data and half that is wrong and you don’t know which half - LORD KELVIN

 

[hokie66]

Thanks for posting those, slickdeals. A lot of folks don't know how difficult it is to develop moment around an opening corner.

 

[msquared48]

Slick post Slick.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[donaldjr87]

Thanks for the article, slickdeals.