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RE: Square Steel Tube Column Got Deflected/Damaged

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Sam,

1. Should I consider P-delta?
Yes.  This is the same as the leaning column issue.  

2. Should it be pulled (jacked) back to a plumb position?
Probably not.  It needs to be straightened in a controlled manner.  You may
want to consider heat straightening by a qualified company.  

3. Should additional reinforcement be added on to this steel column?
This is a viable option.  It would depend on the costs of adding
reinforcement to accommodate the bend as opposed to straightening the
column.  

What are you recommendations?
I would be inclined to add plates and reinforce the column.  They have hit
the column once.  They are inclined to do it again.  

Regards,
Harold O. Sprague


-----Original Message-----
From: Sam Chang [mailto:szchang(--nospam--at)mail.arc.nasa.gov] 
Sent: Tuesday, May 04, 2004 1:25 AM
To: seaint(--nospam--at)seaint.org
Subject: Square Steel Tube Column Got Deflected/Damaged


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?

Thanks

Sam Chang, SE


ps: I have many digital pictures of the condition.  I can e-mail it to you 
if you send me a request  at "szchang(--nospam--at)pacbell.net" .



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