Adding a Timber POST to a steel POST = OK?

[jonnywalker]

The structure is in the middle of construction, and the builders have found a layout problem:

A the top levels of a 3 story structure sit on a steel beam which is supported by a steel column. The builders have discovered that the walls above do not sit on top of the steel beam below. They would like to offset the steel beam from the steel column.

This beam/post only supports gravity loads, but adding and offset post will create a moment in the column due to the added eccentricity that the column cannot support.

The base plate and column are already bolted down. The column has stud bolts welded to the side so that nailers can be countersunk on.

Can they use these studs to attached a full height timber post to the side of the column?

In my head it seems like there would be a problem because of the new nonhomogeneous materiel, but both posts, steel and timber, can easily take 1/2 of the axial load.

Any thoughts without a picture???

 

[JAE]

The steel modulus of elasticity, E = 29000 ksi.
Wood's E value is about 1200 to 1600 ksi. A multiple difference of 24 times.

The wood might not help much because of that and I certainly wouldn't count on any composite behavior between the two.

If the wood post is directly below the beam, then perhaps the load would come down direct on the wood and the steel would serve as a lateral brace to the wood.

How is the beam attached to the two?

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[jayrod12]

No thoughts without pictures. Or at a bare minimum a sketch. How much is the offset? I.e. how far did off did they frame the wall above from the beam below?

 

[EngineeringEric]

This will not work and seems like a bad idea. The two elements will not share the load. what happens to the load in the lower levels? where does the wood column concentrated load go? how do you guarantee the transfer of load to the steel system? Why not move the wall? Why not unbolt the column and move it over? Bolts are easy to remove, almost as easy as installing some argue.
Follow the load all the way down to the foundation. Loads like clean paths, the simpler the better!

 

[msquared48]

The wood column will never get vertically loaded with the steel column there. He is kidding himself.

Mike McCann, PE, SE (WA)

 

[jonnywalker]

Thanks everyone.

I had the same feeling as most everyone above: the steel is stiff and will take the load and the timber wouldnt do much. Another engineer was sure it would be ok. (What?)

to answer a few of the questions:

The W12x is offset 4" max and 1" min.
There is a concrete curb on either side of the base plate and the post connection cannot be moved.
This is a raised podium design so the footing can accommodate the relocated concentrated load. The beam attaches to a top plate that is welded to the top of the steel column.

 

[hokie66]

Rather than wood, I would add some more steel to the column.

 

[idecharlotte]

Not sure why the beam can't remain in place and transfer the wall load to the beam in a more creative way, but a sketch would help.

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