Aluminum columns

[ren ramsey]

Anyone know if these aluminum columns are suitable for load bearing applications. They pliths and tops are separate and they do not bear any weight. They had about 6 holding up a second floor. Course they had them sitting on trex so I know that is wrong. http://i333.photobucket.com/albums/m378/ramdino/IMG_0776.jpg (http://s333.photobucket.com/user/ramdino/media/IMG_0776.jpg.html)

[Jerry Peck]

Did you lift the bases around the columns up and look inside?

Most of those that I've seen (all of them that I can recall) were designed where the columns were slipped into the bases and the based secured with small set screws cranked into the columns to keep the bases down. Inside the columns one typically finds 4x4, 4x6, or 6x6 wood posts.

If there are wood posts inside the metal columns, it is possible that the columns were actually bearing through the composite decking and on bearing below the deck. Maybe not likely, but possible.

[Rick Cantrell]

Maybe not likely, but possible.

I disagree.
What you described, I think is likely.

[Jerry Peck]

I disagree.
What you described, I think is likely.

Rick,

"I think is likely."

Are you referring to the part about having wood columns inside?

Or the part about bearing on supports below the deck?

My "not likely" was referring to the bearing on supports below the deck part.

I suspect your "likely" part is referring to the having wood columns inside part.

[Rick Cantrell]

Yes to both
If the columns did not have internal support, I suspect they would deform under the weight of the upper floor and roof.
If there was only composite decking holding the load, I suspect there would be visible evidence of no support.
Of course I'm basing this on there being a load from the upper floor and roof.
The columns could be decorative, and the upper floor is cantilevered. Though I don't think that is very likely.

[Jerry Peck]

If the columns did not have internal support, I suspect they would deform under the weight of the upper floor and roof.
If there was only composite decking holding the load, I suspect there would be visible evidence of no support.

I'm not so sure as there are six of those columns and I've seen them hold up and support a lot of load without buckling where used where they should not have been used. One main thing is that there is no uplift resistance (something we have to address down here) with a column setting on the floor and a beam setting on the column and nothing is strapped together.

I'm thinking no support and no flexing of the deck because the columns are so close to the nail (screw) lines in the composite decking have the columns close to the joists under the composite decking but not close enough for a post to go next to the joist and up through the columns ... or maybe I'm just looking at the spacing wrong and they are close enough to have a column attached to a joist? If the columns do go through, then the floor joists may be attached to the columns with the columns as support for the deck.

Could very well be??

[Mark Reinmiller]

Yes, hollow aluminum columns like that are made for structural support. You can Google it for details to see similar columns.

[Jim Luttrall]

Yes, hollow aluminum columns like that are made for structural support. You can Google it for details to see similar columns.
The columns are quite strong and rated for substantial loads. The bearing surface is hidden obviously and might present problems.

[Rick Cantrell]

The OP stated the bases were not supporting the columns.
I could be wrong, but I think supporting columns sit on a supporting base.

[ren ramsey]

No I did not take the column base off to look at it. I did look at the top bearing and saw where it was not bearing on much. The picture does not show it but the outside girder for the 2nd floor is on the outside third of the column.http://i333.photobucket.com/albums/m378/ramdino/IMG_0782.jpg (http://s333.photobucket.com/user/ramdino/media/IMG_0782.jpg.html)

- - - Updated - - -

I also found an entire addition that turned out to be built by enclosing an aluminum carport. here is the addition with plywood sheeting and shingles and the other pic is the attic area showing the aluminum structure of the carport. Since I told them to get an engineer to look at this one I figured he could look at the columns too.http://i333.photobucket.com/albums/m378/ramdino/IMG_0829.jpg (http://s333.photobucket.com/user/ramdino/media/IMG_0829.jpg.html)http://i333.photobucket.com/albums/m378/ramdino/IMG_0828.jpg (http://s333.photobucket.com/user/ramdino/media/IMG_0828.jpg.html)

[Jerry Peck]

The addition looks like screen enclosure framing, and not even large screen enclosure framing at that.

Yes Sir ... the structural engineer needs to address the addition and the columns.

Looks like open deck flooring above the columns, I wonder how much water gets down into the columns and how fast it drains out?

[Jim Luttrall]

I have used columns of that type and they were plenty strong for my purposes of supporting a ceiling and porch roof, but they are just an open tube with thin fluted aluminum around the perimeter of the column, think hollow pipe. The larger the diameter of the column, the more weight bearing capacity they have. But they do need solid bearing, not like what you show in the photos. The end caps are merely decorative with no weight bearing capacity, just a set screw holds it in place. They might have a solid end cap as mentioned that is weight bearing in design but I have not seen that for this type of column.

[Garry Sorrells]

Composit and wood columns are rated 5,000 to 10,000 lbs.
Aluminum columns are around 10,000 to 20,000 lbs.
Larger diameter higher rating, All hollow with no interior 4x4 or 6x6 added.
The question is what they are sitting on and how they are supported below that.

There are others that are a 4x4 or 6x6 wood post with a 2 piece aluminum/vinyl/fiberglass cap/cover over the post. The cover has no load rating that I know of. They are basically cosmetic covering.

[Jerry Peck]

There are others that are a 4x4 or 6x6 wood post with a 2 piece aluminum cap/cover over the post. The cover has no load rating that I know of. They are basically cosmetic covering.

Those are the ones I've seen and was referring to.

[Rick Cantrell]

Those are the ones I've seen and was referring to.
Likewise

[Garry Sorrells]

After a little peculating the picture of the top of the column rang a few bells, had to add something else.

The load bearing capacity of the column is based on the load being distributed over the entire surface of the column and that the column is installed plumb.

So, if the load is not centered and evenly distributed then its load bearing capacity is diminished. Sorry I don't have any data/specifications on the load capacity as it moves off center.

In the OP case of top of the column resting off center it may be a cause of concern. Depends on column manufacture and their specifications and the load being carried. Also how the beam load is being distributed to the column.

The compression of the Trex as the column sitting on it may not be a great issue though I would have the column base resiting on an aluminum plate so the edge of the column would not wear/eat its way into the Trex over time. The Trex will expand and contract with temperature up to 1/4 inch. The Trex issue is not so much as its compression as is about how the Trex is supported from below. Trex will not carry much load unsupported. Its span as a deck surface is 16 inches.


PS> Aluminum load bearing columns can come as one piece, but typically come as two pieces. So, seeing a two piece column is not the determining factor of load bearing capabilities or lack of capability. It all depends on the column manufacture design.