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High point loads on continuous basement walls

High point loads on continuous basement walls

High point loads on continuous basement walls

(OP)
Hello!

I have some questions regarding continuous basement walls, loaded with high loads from column.
The question is how to deal with the high vertical point loads.

- Is it correct to adopt a strut-and-tie philosophy and reinforce for the horizontal tensile forces in the top of the wall (and some further down aswell)?
- Is it needed to calculate reduced node capacity with regards to biaxial stress state (CCT-node)? Or can you adopt a 'column representation' and calculate the compressive capacity in the wall.

Would be thankful if someone has any ideas on this!

RE: High point loads on continuous basement walls

One of the weaknesses of strut and tie is that it become excessively onerous once things get a little complicated:

1) I like strut and tie as you've shown it which is as a means of dealing with load spread, independently of other stuff.

2) A column representation would be exactly my approach here.

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: High point loads on continuous basement walls

Some containment reinforcing to accommodate tensile stresses in the vicinity of the point loads... consider it like post-tensioned anchor reinforcing/containment if need be... other than that if you have competent bedrock, I don't see any issue... no need for strut and tie. There are lots of elastic solutions to stresses in the vicinity of concentrated loadings.

Column reinforcing may contribute to additional cracking... How high are your bearing stresses?

Dik

RE: High point loads on continuous basement walls

This depends on the type of column, the relative width of the column and wall, and whether there is a slab at the level where the column and wall meet. I can imagine all types of details.

RE: High point loads on continuous basement walls

My approach to this, for analyzing the wall, would depend on what I intend to do for foundations.
On a recent project, I went with your approach 2. I treated the wall as a column and placed a spread footing directly under the point load.

I would have no objection to distributing the load horizontally across the wall, provided the wall is tall enough to get relatively uniform loading with the loads spreading out at 35deg +/- from the point loads. The foundation would then be a strip footing, wider than you'd have with "approach 2".

Your sketch shows a pretty tall wall, I have a hard time imagining that tensile reinforcing is required. I always think of these in terms of shear failures along a 35deg-45deg line. If you wall is deep enough to distribute the load via this mechanism without any shear issues, do you need tensile reinforcing?

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