Column loaded on its web only

[Ipetu]

A W10x49 x 25' tall column is loaded concentrically but the load is applied only to the column web. The load is 40 kips unfactored. Does the column web need to be analyzed as a slender plate subject to axial load? Or, can it be assumed that the load will find its way into the entire cross section of the column? Thanks.

 

[ToadJones]

I think it is safe to say that after some "shear lag" distance, the full section will be effective in carrying the load.

 

[Lion06]

I agree with toad - it has to. I might still do a local check on the web depending on the detail of the support condition.

 

[JAE]

How is 40 kips of load applied to the web only? What is the connection?

 

[Ipetu]

JAE,

The load is applied via a "shoe" for two jacks. The shoe is in the shape of an inverted U. The top of the inverted U bears on the column web. At the bottom of the legs of the U are stiffened seats for the jacks to sit on. One jack on each side of the column web.

 

[hokie66]

You may be concerned about the wrong thing. The local stress on the web is not likely a problem. However, as you are loading the column at the top, you have to consider how the column works globally. If it is unbraced for its full height, then it is a 'flagpole'.

 

[rb1957]

ipetu,

from your last post, i had a really clear picture in my mind for what you were describing ... only my picture was a beam, with the inverted Us [no, not ewes] being simple supports ?

maybe a pic ??

 

[MikeHalloran]

The load is concentric only if the two jacks are perfectly balanced.

Never happens.


Mike Halloran
Pembroke Pines, FL, USA

 

[ToadJones]

Mike-
I agree, but...
there are some pretty sophisticated jacking systems these days that can get you pretty damn close.
We have used some pancake jacks for very heavy lifts and the things were amazingly accurate.

 

[rb1957]

if it is a column, being lifted by two jacks ... why the heck wouldn't you put an end plate on the column ?

instead of two small jacks, maybe one big one ?

is the column braced laterally, so that imbalance between the jacks can be reacted ?

 

[ToadJones]

rb1957-
I wondered the exact same thing but figured there had to be a reason...