Existing column ties cut
Existing column ties cut
(OP)
We have found when we removed an 8 foot length of hollow sounding concrete on one face of a 40 year old existing column, that all the column ties have been cut out on that face, so that there is nothing tying the #8 corner bars of that face. In fact, at least one of the corner bars has been also cut out and we are still investigating whether the other corner bar is there or not - so far we have not found it. The column is irregularly shape, with 5 corners rather than the normal 4. We don't know if the bar removal was done at the time of original construction, although I suspect so. I suspect it was done perhaps because the bars were showing on the surface due to lack of cover.
Question: In the design of a column, is it assumed that the ties and vertical bars provide confinement to the core of the column? If that be the case, it may be difficult to check this column strength by the normal procedures. On the other hand it will not be easy to add back the ties and missing verticals) even if we build out the concrete.
Question: In the design of a column, is it assumed that the ties and vertical bars provide confinement to the core of the column? If that be the case, it may be difficult to check this column strength by the normal procedures. On the other hand it will not be easy to add back the ties and missing verticals) even if we build out the concrete.






RE: Existing column ties cut
RE: Existing column ties cut
RE: Existing column ties cut
RE: Existing column ties cut
RE: Existing column ties cut
RE: Existing column ties cut
What you do is fabricate steel bands - perhaps 3/8" thick x 3" wide - around the column where the ties originally were intended to go.
The straps would be carefully fabricated to be just a bit short on each face. The contractor can flame heat these straps to expand slightly and
then install on the column. The ends of the straps are either bolted or welded together. As it cools it tightens on the column.
For the vertical bars, it might be best to chip away at the concrete cover and expose the bars such that you can supplement the vertical bars with new bars.
These might have to lap the existing bars or be welded onto them. Even if they aren't A706 weldable bars, you might be able to figure out the chemistry to get a good weld.
For a single cut bar, use two adjacent bars to keep the steel-bar configuration symmetrical.
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