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RE: Square Steel Tube Column Got Deflected/Damaged

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It sounds like the column itself is relatively undamaged, in which case it
should not be necessary to reinforce the column.  The added axial load is
well within the allowable.

P-delta is a real issue but it is not resisted by the column.  In this case
the P-delta forces will be resisted by the roof system acting as a
diaphragm that transfers the horizontal forces to the lateral system. 
P-delta is a story phenomena and cannot in general be resolved by looking
at individual columns.

If the column is leaning then there is not bending in the column due to the
P-delta effect, thus calculations of bending are not very relevant.

Of more concern is where the real damage occured.  If the column is
straight, but leaning, then the movement must be acommodated at some other
location.  Find the location where the distortion occured and you will find
out if you have a problem.

Mark Gilligan


Message text written by INTERNET:seaint(--nospam--at)seaint.org
>--------------------------------------------------------------------------

In a tilt-up type of building that was built in 1980 in Northern 
California, a square tube column HSS5x5x3/16 was bumped by some vehicle 
that crated a permanent measurable deflection of 1.5 inches from the 
ceiling level to the floor.

Floor to the top of the girder is about 17 feet height.  The girder above 
is 5.125"by30"glu-lam girder.  This column deflects along the same 
direction of the glu-lam girder. The columns are spaced at 53.5 feet and 
girders are spaced at 22.5 feet.

(15DL+12LL)*22.5*53.5 = 18.1 kip DL + 14.5 kip LL = 32.6 kips

AISC ASD Column Table has allowable P-load capacity (L=17ft) = 47 kips 
which takes out about 70% of column capacity.

If I take the P-delta into consideration the M = 48.9 kip-inch:

Sxx = 5.03 in^3, Bending stress to the HHS = 9.72 ksi which takes out about

35% of pure bending capacity.

This column is not a part of lateral-resisting-frame.

The column was probably design as pined-pined connection.

Questions:

1. Should I consider P-delta?

2. Should it be pulled (jacked) back to a plumb position?

3. Should additional reinforcement be added on to this steel column?

What are you recommendations?<


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