Corrosion steel columns. 1

[connect2]

Have the following situation, opinions welcome;

Steel columns in a parking garage carrying a large dbl. gymnasium, per cast concrete dbl.tee's, and roof built of structural steel and owsj over the gymnasium. Fair spans in all directions. Corrosion of about 25% of section interior columns and about 10% exterior columns. All columns sit on spread footings with their base plates below the finished grade of the parking structure with the corrosion extending from the base plate, +/- 12" below grade to +/- 12 " above grade. Built in 1954, the columns had sufficient capacity, seismic aside. Question then??

Prep. columns to base metal of uncorroded steel and add plate ?,

or,

Shore structure (ouch $$$), and replace bottoms of columns with new concrete piers to +/- 12" above grade.

or,

some other ideas?

By the way SlideRuleEra, if you read this post, copied some stuff off your website, thank-you.

 

[JAE]

The type of fix depends on the space available around the columns.

If there is adequate space, one way would be to clean the columns, weld on headed studs, wrap with reinforcing and encase the columns in a round concrete collar, extending from the footing (doweled in) and extend up a distance neceswsary to transfer the axial load from the steel column through the studs into the concrete.

For steel on steel repairs or strengthening, I'd be inclinded to shore up the adjoining beams and/or column section itself (above the fix) prior to welding onto the shape.

What you can do is look at the actual in-place stress level of the columns (dead load only perhaps) and carefully weld on limited portions of the column at one time.

 

[SlideRuleEra]

connect2 - Thanks, the website is a lot of fun to maintain and add to.

About your question, I like JAE's concrete collars. That minimizes modification to the existing steel. Anytime you unnecessarily weld, drill, cut, etc. stressed existing material, you are asking for trouble.

http://www.SlideRuleEra.net