On May 20, 6:44*am, "Tom Cular" wrote:
Fire protection of structural steel is placed on the exterior of the
members, not within a pipe or tube.

To make it simple, take a look at a typical pipe pile, driven empty, then
filled with concrete, with a circular cage reinforcing only in the upper
section (top 20-30'), a vertical bar or two near the center does nothing.

As Matt and Rico have stated the concrete fill is to resist buckling.

Tom

"Stormin Mormon" wrote in message

...



When I was in college, so many years ago. We learned that cement is strong
for compressive loads (such as columns in the cellar). Steel is good for
stretching loads (hanging a bridge from a frame).

If your friend's use of concrete is to support weight, it may work very
well. Concrete often has reinforcing bar, or rebar. This steel helps to
combine the compression strength of concrete with the stretching strength
of
steel.

--
Christopher A. Young
Learn more about Jesus
*www.lds.org
.

"Thomas G. Marshall"
. com
wrote in messagenews:ib_Xj.134$ay2.84@trndny01...

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?- Hide quoted text -

- Show quoted text -


And I would submit that it does a lot more than just provide the
buckling resistance. Concrete is widely used to form structural
support to hold up buildings, bridges, etc. Even in this deck
example, what are the footers made of? They are essentially
cylindrical concrete pillars. So, while the concrete does keep the
steel pipes in a lolly column from buckling, which is clearly
important, the concrete also carries some of the weight directly. If
instead of concrete, you had some other means to keep the column from
buckling, say an internal criss cross web of little rods, I would say
the concrete filled lolly would carry substantially more weight.