DIYbanter - View Single Post - Disaster waiting to happen? Using PVC for deck supports???

Edward Hennessey

Matt Whiting wrote:
wrote:
On Sun, 18 May 2008 18:28:11 -0400, Matt Whiting
wrote:
wrote:
On Sun, 18 May 2008 18:02:54 GMT, "Thomas G. Marshall"
. com wrote:

There was a person I was speaking to recently who was proud of
what he considered to be a very bright move on his part.

He had noticed that the lolly-columns in his basement had been
filled with cement prior to being used. He assumed that the
strength of the support was in the cement, and therefore
concluded it was a good idea to try filling PVC tubes and using
those as posts (note-not as sonno-tubes, but as fully structural
support posts). I pointed out that I thought that the strength of a
lolly was in
the steel, and that the cement was there merely to ensure that it
was never dented, causing it to fold like an aluminum can. I was
concerned that the first major frost heave under his deck that is
able to stress the ledger enough to pull outward a small amount
would cause his pvc+cement "posts" to break. Was I right?

The concrete in steel lolly columns is to help keep them from
collapsing in a fire.
It also does provide much improved buckling resistance.

Yes, buckling that would be caused by the heat of a FIRE.

No, buckling caused by heavy load as well. A column doesn't need fire
to buckle.

Matt

M:

Although no one addressed the question, the geophysical stability of the
location would
be of some measured consideration. Performance of the columns on soil
subject to liquefaction in a seismic event merits concern in the right
circumstances.
A first-hand look at the density of steel used in the recent rebuilds of
L.A.
freeway overpass supports is amazing.

Whether the OP or owner has further interest in possible remedies for any
shortcomings in this case is a another question.

Regards,

Edward Hennessey