How to correct the out of the plumbness of column during erection

[cemichaelliu]

Hi Everyone,

I need help on how to correct the out-of-plumbness of column. During the erection of a stair tower module, the survey shows that the column is way out of the H/500 plumbness at each level, and out of plumb in different directions.

Much appreciated that you can shed some light on proposal in correcting those out of plumnbess of column?

Thank you

 

[spats]

The question is too general to give a meaningful answer. You need to describe your condition in more detail. You also sometimes need to ask yourself if you can live with the out-of-plumb, even if it is out of specs.

 

[MiketheEngineer]

A really big hammer

 

[MikeHalloran]

That's normally worked out between the erector and the fabricator, and yes, often really does involve big hammers, or smoke wrenches.


Mike Halloran
Pembroke Pines, FL, USA

 

[ToadJones]

Bracing, Come alongs, wedges etc...
Usually a plumbing and rattling gang takes care of making sure each level of construction is plumbed properly and then torques bolts prior to moving on to the next phase.

 

[MiketheEngineer]

I believe the New Orleans Superdome was out of "plumb" and they literally banged it back into line with headache balls!!

The St. Louis Arch was slightly out of alignment when they "closed" the top. Actually wasn't too far off considering it is 630' tall and 630'wide and done without lasers, etc They used specially constructed hydraulic jacks to push and shove the two legs into place and "popped" the last piece in place.

 

[CTW]

I thought the issue with the arch was too much expansion due to heat. The jacks were used to open the gap to allow the last piece to fit.

 

[MiketheEngineer]

CTW -

Actually - both

The south leg started to heat up with the sun rising and of course gravity "pulled" the legs together. Firefighters hosed the south leg - but could only reach up so high. They were also slightly off up/down and left/right - but nothing much!!

If you ever visit the Arch - stay and see the 30 minute movie on its construction. Quite amazing. They show it on the Discovery or TLC channel from time to time.

Most amazing - no one died during construction. If you watch the movie you will notice a lack of hard hats, safety belts, tie-offs, etc and NOTHING on it was level or square!!

 

[dhengr]

You might first want to try to understand what has caused the out-of-plumb column conditions, what directs, how much, etc. Actually plot this out on some simple plans and elevations. Are the columns straight, but out-of-plumb? Are you using a two foot level or surveying equip. to check the field conditions? Check shop drwgs. and actual pieces in the field, are they causing the problems? Are there any unusual fit-up or connection conditions causing the problems? Only then can you start to determine a fix. But, this is primarily a fabricator and steel erection sub problem so they should foot the bill on this. How much other construction has been completed around the steel, which of course complicates the fix? Is this just sloppy work on the part of the erection sub?

 

[cemichaelliu]

Thank you all for your response.

I will have to discuss with the client to see whether they accept the "out-of-plumbness" if the structures is checked and and found sound after considering this "out of plumbness".

 

[SAIL3]

Also check if the correction method will induce loads at the fdn....if so, one could loosen the anchor bolts temporarily to accomodate any rotation, etc. if this does not cause instability of the structure...

 

[southard2]

See if it works out of plumb. If it is a braced frame make sure you capture the moment amplification effects of little delta. If they force the columns back into alignment all you are doing is permanently storing the energy. You might be able to find the problem in the steel shop drawings. Perhaps a beam was fabbed to short, etc.... and so they forced it to fit.

John Southard, M.S., P.E.

http://www.pdhlibrary.com