Basement Wall Corners: Horizontal Bar Development 1

[Delchi]

It is common practice to analyze basement walls using tank-tables, which usually indicate high negative moments around corners and at counterforts. My question is how the bars around corners can be used for tension reinforcement in walls that are too thin to allow the minimum hooked-bar development length.

For example, how can the negative moments be resisted at the corners of an 8" or 9" basement wall when the horizontal reinforcing consists of #5 bars? (In the case where the backfilling and compacting would be performed prior to framing the floor)

I would appreciate any thoughts on how the corner conditions can be detailed in accordance with the ACI 318. Thanks!

 

[BAretired]

Delchi,

For example, how can the negative moments be resisted at the corners of an 8" or 9" basement wall when the horizontal reinforcing consists of #5 bars? (In the case where the backfilling and compacting would be performed prior to framing the floor)

First of all, it is generally not a good practice to backfill and compact prior to framing the floor. Better to avoid that by placing both floors before backfilling all the way to the top.

I do not see any problem in developing #5 bars on the exterior face of the wall at a corner. The problem in a rectangular tank occurs on the inside face with water pressure pushing outward, creating tension on the inside face at the corners. You don't have that situation so where is the problem?

BA

 

[NoName1]

Splitrings and VTEIT,

Sorry to post a question in another post, but i have been wondering about what you brought up.

When you reduce the spacing at the corners, is that total amount of steel provided at the corner the amount required by analysis for the moment at the corner and the reinforcing along the wall would be for the moment as it drops off? Or is the steel at half spacing in the corner in addition to what is required by analysis?

Thanks.

 

[Splitrings]

NoName1,
The additional steel in the corners is what is required by analysis. This addtional steel continues along each of the walls until the moment drops to a point where the wall reinforcing is sufficient.

 

[NoName1]

Thank you for the response.