what is the best way to repair this 2

[delagina]

what is the best way to repair this column?

 

[mfrad]

Make sure that that column is vertically reinforced. Outside of a dowel at the bottom I don't see any vertical bars against the spiral. Exposé other side of column.

Send a sample of the concrete cover for chloride and petrographic analysis.

 

[TXStructural]

I agree with everything already said. That column does not look healthy, and we need to know why it is spalling before giving too much advice. It does look like there is a weak plane at the narrowly-pitched spiral, under poorly-consolidated concrete cover, which may have been pushed off by corrosion products. And it was apparently formed with a cardboard tube, which is unusual for commercial, structural concrete.

You may have lost sufficient section of the spiral to justify a good washdown and installation of new confinement steel before replacing the cover. If you want to add an FRP layer for confinement, you probably need to have a smoother surface and the existing steel needs protection from further corrosion (by replacing the cover.)

 

[racookpe1978]

Given the time, money, and effort (and did we mention the money involved) and risk of future failure of concrete again, could he "replace" the circular concrete column with a steel hollow section arounnd the old concrete? It would require splitting the steel hollow section, putting the two halves around the concrete, and welding up both side joints; and a good foundation link or plate at the base, a good tie-in at the top, but both are needed anyway of the concrete is replaced with a thicker section by wrapping or re-concreting the outside of the current column.

A square column could work as well, which would provide a "form" to pour new concrete inside the HSS member as well if concrete is replaced.