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Re: Bent column

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Regarding the damaged column capacity.

The Euler buckling load is an upper bounds solution with an initial displacement
equal to zero.  The ASD allowable stresses are based on that.  For LRFD, an
initial displacement of L/1500 was used, resulting in a buckling capacity of
0.877 times the Euler buckling load.  Your 1/2 inch displacement for a 26 foot
column is L/600.  Your elastic buckling strength has been considerably reduced
by the fork lift.  You need to adjust either your ASD allowable axial stress or
your LRFD axial strength for your situation.  In combination with the P-delta
bending moment for the maximum roof load, hopefully you will still be OK.

Rick Drake, SE
Fluor Daniel, Aliso Viejo

***********************************************





"Jesse D. Moore" <jdmse(--nospam--at)inreach.com> on 02/18/2000 09:20:22 AM

Please respond to seaint(--nospam--at)seaint.org

To:   seaint(--nospam--at)seaint.org
cc:    (bcc: Rick Drake/AV/FD/FluorCorp)

Subject:  Bent column



Greetings,


I've inspected a damaged roof column on one of my projects which I am the EOR.
Concrete tilt-up building w/panelized roof system. The building is under
construction and the roof is in place. The column is a TS6x6x3/8 (unsupported
ht=26') and was struck by a forklift bending it approx ½" max at 6' above top of
slab. No local deformation noted at the point of impact. There are several
cracks propagating from the anchor rods through the grout under the base plate.


I'm thinking of removing the grout and pull-testing the anchor rods. The column
will easily calculate with the new eccentricity. But haven't the material
properties of the column changed locally due to the plastic deformation? And how
does this affect column behavior?


Any insight will be appreciated.


Jess

Greetings,

I’ve inspected a damaged roof column on one of my projects which I am the EOR. Concrete tilt-up building w/panelized roof system. The building is under construction and the roof is in place. The column is a TS6x6x3/8 (unsupported ht=26’) and was struck by a forklift bending it approx ½" max at 6’ above top of slab. No local deformation noted at the point of impact. There are several cracks propagating from the anchor rods through the grout under the base plate.

I’m thinking of removing the grout and pull-testing the anchor rods. The column will easily calculate with the new eccentricity. But haven’t the material properties of the column changed locally due to the plastic deformation? And how does this affect column behavior?

Any insight will be appreciated.

Jess