DIYbanter

DIYbanter (https://www.diybanter.com/)
-   Home Repair (https://www.diybanter.com/home-repair/)
-   -   Disaster waiting to happen? Using PVC for deck supports??? (https://www.diybanter.com/home-repair/250511-disaster-waiting-happen-using-pvc-deck-supports.html)

Thomas G. Marshall May 18th 08 08:02 PM

Disaster waiting to happen? Using PVC for deck supports???
 


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?




EXT May 18th 08 09:04 PM

Disaster waiting to happen? Using PVC for deck supports???
 
It probably depends on the diameter of the PVC tube. A 3" or 4" will not
have much strength, especially if there is not a continuous large diameter
re-bar down the middle. I can see the PVC cracking in cold weather,
particularly if the top is able to soak up some water that freezes.

A 6" or 8" PVC tube with three or four re-bars, probably would be no more
than a vinyl coated concrete column, and look good compared to bare
concrete. The concrete will take most of the load. I can see the same
problems with freezing water however. It could be difficult to make a
connection with the foundation unless the post is run all the way down to
the footing.


"Thomas G. Marshall" . com
wrote in message news: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?





RicodJour May 18th 08 09:36 PM

Disaster waiting to happen? Using PVC for deck supports???
 
On May 18, 2:02 pm, "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?


I think you're right that there's cause for concern, I think you're
wrong about the failure mechanism unless the footings are seriously
sub-standard, and I think there's a lot of information left out. The
diameter of the PVC, whether it's Schedule 40 or 80 or even the thin
stuff that they use for drainage, how deep the footings are, how high
above grade the deck is, etc.

R

curt[_2_] May 18th 08 11:12 PM

Disaster waiting to happen? Using PVC for deck supports???
 
On Sun, 18 May 2008 12:36:06 -0700, RicodJour wrote:


I think you're right that there's cause for concern, I think you're
wrong about the failure mechanism unless the footings are seriously
sub-standard, and I think there's a lot of information left out. The
diameter of the PVC, whether it's Schedule 40 or 80 or even the thin
stuff that they use for drainage, how deep the footings are, how high
above grade the deck is, etc.

R


If I remember correctly, Schedule 80 is called for on all deck support
posts.


Thomas G. Marshall May 18th 08 11:20 PM

Disaster waiting to happen? Using PVC for deck supports???
 
curt said something like:
On Sun, 18 May 2008 12:36:06 -0700, RicodJour wrote:


I think you're right that there's cause for concern, I think you're
wrong about the failure mechanism unless the footings are seriously
sub-standard, and I think there's a lot of information left out. The
diameter of the PVC, whether it's Schedule 40 or 80 or even the thin
stuff that they use for drainage, how deep the footings are, how high
above grade the deck is, etc.

R


If I remember correctly, Schedule 80 is called for on all deck support
posts.


Implication question: Is PVC meeting schedule-80 requirements considered
acceptable for deck supports?




Thomas G. Marshall May 18th 08 11:21 PM

Disaster waiting to happen? Using PVC for deck supports???
 
said something like:

....[snip]...


The concrete in steel lolly columns is to help keep them from
collapsing in a fire.


.....so the preventing a dent thing is secondary, or not a concern...?



JoeSpareBedroom May 18th 08 11:30 PM

Disaster waiting to happen? Using PVC for deck supports???
 
"Thomas G. Marshall" . com
wrote in message news:z51Yj.138$ay2.70@trndny01...
said something like:

...[snip]...


The concrete in steel lolly columns is to help keep them from
collapsing in a fire.


....so the preventing a dent thing is secondary, or not a concern...?



My interpretation is that the dent thing is completely irrelevant.



Dick Adams[_2_] May 19th 08 12:17 AM

Disaster waiting to happen? Using PVC for deck supports???
 
Thomas G. Marshall . com wrote:

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).


Ignorance is bliss.

I used PVC for my mail box post. Went down 18 inches, carved
out a 3" foot lip, crisscrossed 8" bolt at 6" and 10", filled
with concrete and rebar. My mail box was getting knocked
down by cars sliding on ice.

Someone was knocking down mail boxes with a baseball bat.
The police found him when I told them to check for people
with forearms. This clown broke his forearm and his wrist.

But as a deck support, that's a joke.

Dick


Pete C. May 19th 08 12:25 AM

Disaster waiting to happen? Using PVC for deck supports???
 

"Thomas G. Marshall" 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?


There are code approved PVC pipe based deck support columns available.
The compressive strength of PVC pipe is tremendous as long as you keep
it from buckling. I once tested a 1' length of 4" sch40 PVC pipe in a
hydraulic press and it too over 30 tons of force before it started to
fail (Enerpac press with pressure gauge). The compressive strength of
concrete is also very high. Combined strength is more than adequate and
PVC handles cold pretty well also.

Matt Whiting May 19th 08 12:28 AM

Disaster waiting to happen? Using PVC for deck supports???
 
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.

The PVC filled column is a very dumb idea unless an engineer has
computed the capacity of the column and sized it appropriately for the
anticipated loads.

Matt

Matt Whiting May 19th 08 12:28 AM

Disaster waiting to happen? Using PVC for deck supports???
 
Thomas G. Marshall wrote:
said something like:

...[snip]...


The concrete in steel lolly columns is to help keep them from
collapsing in a fire.


....so the preventing a dent thing is secondary, or not a concern...?



No, preventing buckling is a significant advantage provided by filling a
steel column.

Matt

Matt Whiting May 19th 08 12:29 AM

Disaster waiting to happen? Using PVC for deck supports???
 
JoeSpareBedroom wrote:
"Thomas G. Marshall" . com
wrote in message news:z51Yj.138$ay2.70@trndny01...
said something like:

...[snip]...


The concrete in steel lolly columns is to help keep them from
collapsing in a fire.

....so the preventing a dent thing is secondary, or not a concern...?



My interpretation is that the dent thing is completely irrelevant.



Your interpretation is incorrect.

Matt

JoeSpareBedroom May 19th 08 12:41 AM

Disaster waiting to happen? Using PVC for deck supports???
 
"Matt Whiting" wrote in message
. ..
JoeSpareBedroom wrote:
"Thomas G. Marshall"
. com wrote in message
news:z51Yj.138$ay2.70@trndny01...
said something like:

...[snip]...


The concrete in steel lolly columns is to help keep them from
collapsing in a fire.
....so the preventing a dent thing is secondary, or not a concern...?



My interpretation is that the dent thing is completely irrelevant.


Your interpretation is incorrect.

Matt



OK.



Matt Whiting May 19th 08 12:58 AM

Disaster waiting to happen? Using PVC for deck supports???
 
Pete C. wrote:
"Thomas G. Marshall" 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?


There are code approved PVC pipe based deck support columns available.
The compressive strength of PVC pipe is tremendous as long as you keep
it from buckling. I once tested a 1' length of 4" sch40 PVC pipe in a
hydraulic press and it too over 30 tons of force before it started to
fail (Enerpac press with pressure gauge). The compressive strength of
concrete is also very high. Combined strength is more than adequate and
PVC handles cold pretty well also.



I'd hardly call it tremendous. 8300 psi exceed most standard concrete,
although high strength concrete is available now that substantially
exceeds this value. And this falls FAR short of even standard A36 steel.


http://www.harvel.com/piping-clear-pvc.asp

Pete C. May 19th 08 01:55 AM

Disaster waiting to happen? Using PVC for deck supports???
 

Matt Whiting wrote:

Pete C. wrote:
"Thomas G. Marshall" 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?


There are code approved PVC pipe based deck support columns available.
The compressive strength of PVC pipe is tremendous as long as you keep
it from buckling. I once tested a 1' length of 4" sch40 PVC pipe in a
hydraulic press and it too over 30 tons of force before it started to
fail (Enerpac press with pressure gauge). The compressive strength of
concrete is also very high. Combined strength is more than adequate and
PVC handles cold pretty well also.


I'd hardly call it tremendous. 8300 psi exceed most standard concrete,
although high strength concrete is available now that substantially
exceeds this value. And this falls FAR short of even standard A36 steel.

http://www.harvel.com/piping-clear-pvc.asp


8300 psi? I come up with more like 37,500 psi since this was 4" dia sch
40 PVC pipe with no filling i.e. 60,000# load on something like 1.6
square inches of PVC total.

Lou May 19th 08 02:13 AM

Disaster waiting to happen? Using PVC for deck supports???
 
What am I missing here? The extra cost alone makes it not worth
doing. Not to mention how you would attach them without making
it look jerry rigged. Even if you got past those two items, what would
you make the rest of the deck out of to look right? I suppose if your
only
going 12" off the ground that it wouldn't matter but it sure sounds
like
your taking a step backwards.
Lou


Lou May 19th 08 04:04 AM

Disaster waiting to happen? Using PVC for deck supports???
 

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.


Check the temp that would cause steel to buckle.
Now see what happens to concrete at that temp.
Lou

RicodJour May 19th 08 07:25 AM

Disaster waiting to happen? Using PVC for deck supports???
 
On May 18, 8:45 pm, wrote:
On Sun, 18 May 2008 18:28:48 -0400, Matt Whiting wrote:
Thomas G. Marshall wrote:
said something like:


The concrete in steel lolly columns is to help keep them from
collapsing in a fire.


....so the preventing a dent thing is secondary, or not a concern...?


No, preventing buckling is a significant advantage provided by filling a
steel column.


Uh, yes. And the buckling it prevents would be the result of fire. Filling the
columns with cement is to protect the columns from buckling in a FIRE.


In a wood framed building? I guess if the fire started at the base of
the column that might be a good argument, but in any real situation
the house would be engulfed in flames long before the plastic
temperature of the steel was reached.

The concrete fill is to prevent buckling, partially from being dented,
but also to prevent localized failure which can occur at lower loads
than the straight compressive strength of the material(s) would
indicate.
http://en.wikipedia.org/wiki/Buckling

R

PeterD May 19th 08 02:50 PM

Disaster waiting to happen? Using PVC for deck supports???
 
On Sun, 18 May 2008 17:50:49 -0500, "Glenn" wrote:


"Matt Whiting" wrote in message
. ..

No, preventing buckling is a significant advantage
provided by filling a steel column.

Matt


Whoa, if you are using a steel column, why the
concrete? Sky scrapers sit on steel columns with out
concrete in them. What am I missing?



Perhaps four years of engineering school? Or even two semesters of
structural member strength? g

Thomas G. Marshall May 19th 08 09:36 PM

Disaster waiting to happen? Using PVC for deck supports???
 
RicodJour said something like:
On May 18, 8:45 pm, wrote:
On Sun, 18 May 2008 18:28:48 -0400, Matt Whiting
wrote:
Thomas G. Marshall wrote:
said something like:


The concrete in steel lolly columns is to help keep them from
collapsing in a fire.


....so the preventing a dent thing is secondary, or not a
concern...?


No, preventing buckling is a significant advantage provided by
filling a steel column.


Uh, yes. And the buckling it prevents would be the result of fire.
Filling the columns with cement is to protect the columns from
buckling in a FIRE.


In a wood framed building? I guess if the fire started at the base of
the column that might be a good argument, but in any real situation
the house would be engulfed in flames long before the plastic
temperature of the steel was reached.

The concrete fill is to prevent buckling, partially from being dented,
but also to prevent localized failure which can occur at lower loads
than the straight compressive strength of the material(s) would
indicate.
http://en.wikipedia.org/wiki/Buckling


This makes sense to me, though I'm hardly as versed in structural analysis
as the other denisins of this ng. Fire seems a concern, though secondary,
only because the plasticity of steel could never be reached in a basement
without the rest of the house already having been reduced to dust. Or so it
seems to me. {shrug}





[email protected] May 19th 08 10:30 PM

Disaster waiting to happen? Using PVC for deck supports???
 
On May 18, 6:17*pm, (Dick Adams) wrote:
Someone was knocking down mail boxes with a baseball bat.
The police found him when I told them to check for people
with forearms. *This clown broke his forearm and his wrist.


Good thing the clown was dumb as a the post he broke his arm on
because if he'd had a lick of smarts at all he would've sued you for
the injuries he sustained trying to bash in your mailbox... and he
would've won. You're lucky.

A friend of mine put boulders in his front yard because drunk drivers
had missed the corner and ended up in his front yard on several
occasions, and had hit both his house and his travel trailer at least
once. The insurance company gave him 48 hours to have the boulders
removed or they'd drop his policy. Long and short of it was, the
boulders were a willful admission of wrongdoing/negligence in a
lawsuit because they were put there to protect the house from drunk
drivers. He could say they were decorative all he wanted, all they had
to do in court was point out that the boulders were placed there AFTER
the drunk hit his trailer, and he'd lose.

Lou May 19th 08 11:02 PM

Disaster waiting to happen? Using PVC for deck supports???
 
On May 19, 3:30 pm, wrote:
On May 18, 6:17 pm, (Dick Adams) wrote:

Someone was knocking down mail boxes with a baseball bat.
The police found him when I told them to check for people
with forearms. This clown broke his forearm and his wrist.


Good thing the clown was dumb as a the post he broke his arm on
because if he'd had a lick of smarts at all he would've sued you for
the injuries he sustained trying to bash in your mailbox... and he
would've won. You're lucky.

A friend of mine put boulders in his front yard because drunk drivers
had missed the corner and ended up in his front yard on several
occasions, and had hit both his house and his travel trailer at least
once. The insurance company gave him 48 hours to have the boulders
removed or they'd drop his policy. Long and short of it was, the
boulders were a willful admission of wrongdoing/negligence in a
lawsuit because they were put there to protect the house from drunk
drivers. He could say they were decorative all he wanted, all they had
to do in court was point out that the boulders were placed there AFTER
the drunk hit his trailer, and he'd lose.


Well I'm no attorney but, that doesn't sound right. A drunk driver
doesn't premeditate
getting drunk and running into a house so therefore creates an
accident. An idiot
smashing mailboxes does premeditate the conditions, planning and
carrying out
the plan to destroy private property. He could have sued but my bet
is that it would
have backfired.
Lou

Matt Whiting May 20th 08 12:34 AM

Disaster waiting to happen? Using PVC for deck supports???
 
wrote:
On Sun, 18 May 2008 18:28:48 -0400, Matt Whiting wrote:

Thomas G. Marshall wrote:
said something like:

...[snip]...


The concrete in steel lolly columns is to help keep them from
collapsing in a fire.
....so the preventing a dent thing is secondary, or not a concern...?


No, preventing buckling is a significant advantage provided by filling a
steel column.

Matt


Uh, yes. And the buckling it prevents would be the result of fire. Filling the
columns with cement is to protect the columns from buckling in a FIRE.


It also adds tremendously to normal buckling resistance, not just
buckling resistance due to fire reducing the capacity of the material.

http://www.aisc.org/Content/ContentG...eedings/51.pdf


Matt Whiting May 20th 08 12:36 AM

Disaster waiting to happen? Using PVC for deck supports???
 
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

Matt Whiting May 20th 08 12:38 AM

Disaster waiting to happen? Using PVC for deck supports???
 
Pete C. wrote:
Matt Whiting wrote:
Pete C. wrote:
"Thomas G. Marshall" 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?
There are code approved PVC pipe based deck support columns available.
The compressive strength of PVC pipe is tremendous as long as you keep
it from buckling. I once tested a 1' length of 4" sch40 PVC pipe in a
hydraulic press and it too over 30 tons of force before it started to
fail (Enerpac press with pressure gauge). The compressive strength of
concrete is also very high. Combined strength is more than adequate and
PVC handles cold pretty well also.

I'd hardly call it tremendous. 8300 psi exceed most standard concrete,
although high strength concrete is available now that substantially
exceeds this value. And this falls FAR short of even standard A36 steel.

http://www.harvel.com/piping-clear-pvc.asp


8300 psi? I come up with more like 37,500 psi since this was 4" dia sch
40 PVC pipe with no filling i.e. 60,000# load on something like 1.6
square inches of PVC total.


Material properties don't depend on the size of the pipe. Did you even
open the reference I provided? Do you understand MATERIAL properties?

Matt

Edward Hennessey May 20th 08 04:01 AM

Disaster waiting to happen? Using PVC for deck supports???
 
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



Pete C. May 20th 08 05:04 AM

Disaster waiting to happen? Using PVC for deck supports???
 

Matt Whiting wrote:

Pete C. wrote:
Matt Whiting wrote:
Pete C. wrote:
"Thomas G. Marshall" 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?
There are code approved PVC pipe based deck support columns available.
The compressive strength of PVC pipe is tremendous as long as you keep
it from buckling. I once tested a 1' length of 4" sch40 PVC pipe in a
hydraulic press and it too over 30 tons of force before it started to
fail (Enerpac press with pressure gauge). The compressive strength of
concrete is also very high. Combined strength is more than adequate and
PVC handles cold pretty well also.
I'd hardly call it tremendous. 8300 psi exceed most standard concrete,
although high strength concrete is available now that substantially
exceeds this value. And this falls FAR short of even standard A36 steel.

http://www.harvel.com/piping-clear-pvc.asp


8300 psi? I come up with more like 37,500 psi since this was 4" dia sch
40 PVC pipe with no filling i.e. 60,000# load on something like 1.6
square inches of PVC total.


Material properties don't depend on the size of the pipe. Did you even
open the reference I provided? Do you understand MATERIAL properties?

Matt


Do you understand that under testing in my 50T press, it took a load of
~37,500 PSI on the 1' length of 4" sch 40 PVC pipe before it failed?
Material properties are irrelevant, that was the actual result of the
test I noted.

Tom Cular May 20th 08 12:44 PM

Disaster waiting to happen? Using PVC for deck supports???
 
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 message news: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?







Matt Whiting May 20th 08 12:54 PM

Disaster waiting to happen? Using PVC for deck supports???
 
Pete C. wrote:
Matt Whiting wrote:
Pete C. wrote:
Matt Whiting wrote:
Pete C. wrote:
"Thomas G. Marshall" 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?
There are code approved PVC pipe based deck support columns available.
The compressive strength of PVC pipe is tremendous as long as you keep
it from buckling. I once tested a 1' length of 4" sch40 PVC pipe in a
hydraulic press and it too over 30 tons of force before it started to
fail (Enerpac press with pressure gauge). The compressive strength of
concrete is also very high. Combined strength is more than adequate and
PVC handles cold pretty well also.
I'd hardly call it tremendous. 8300 psi exceed most standard concrete,
although high strength concrete is available now that substantially
exceeds this value. And this falls FAR short of even standard A36 steel.

http://www.harvel.com/piping-clear-pvc.asp
8300 psi? I come up with more like 37,500 psi since this was 4" dia sch
40 PVC pipe with no filling i.e. 60,000# load on something like 1.6
square inches of PVC total.

Material properties don't depend on the size of the pipe. Did you even
open the reference I provided? Do you understand MATERIAL properties?

Matt


Do you understand that under testing in my 50T press, it took a load of
~37,500 PSI on the 1' length of 4" sch 40 PVC pipe before it failed?
Material properties are irrelevant, that was the actual result of the
test I noted.


37,500 psi is a pressure, not a load. Material properties are not only
relevant, they are essential to almost all structural engineering
calculations (I know as I have a masters in civil/structural). And the
behavior of a short column is MUCH different than a long column. Ever
heard of Euler?

A nearly pure compression test (which is what a 1' long 4" pipe
comprises) has almost no relevance to the case of a column that has a
substantially different slenderness ratio and thus subject to a buckling
failure mode as well as possible bending moments due to eccentric loading.

I didn't see a column length in the OP, but when "basement" is the
description rather than "crawl space" it is likely that the length is at
least 6' and possibly 8' or even more. This is far from being a 1'
column. Concrete filled PVC could work if sized properly, but using the
same size as the existing steel column is a fool's errand. Again, the
OP didn't mention the size of either the steel or the PVC, but I'll bet
there were likely nearly the same size. If that is the case, then the
PVC is almost certainly inadequate, unless the steel column was grossly
oversized for the required load.

Matt

[email protected] May 20th 08 02:45 PM

Disaster waiting to happen? Using PVC for deck supports???
 
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.

Pete C. May 20th 08 04:28 PM

Disaster waiting to happen? Using PVC for deck supports???
 

Matt Whiting wrote:

Pete C. wrote:
Matt Whiting wrote:
Pete C. wrote:
Matt Whiting wrote:
Pete C. wrote:
"Thomas G. Marshall" 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?
There are code approved PVC pipe based deck support columns available.
The compressive strength of PVC pipe is tremendous as long as you keep
it from buckling. I once tested a 1' length of 4" sch40 PVC pipe in a
hydraulic press and it too over 30 tons of force before it started to
fail (Enerpac press with pressure gauge). The compressive strength of
concrete is also very high. Combined strength is more than adequate and
PVC handles cold pretty well also.
I'd hardly call it tremendous. 8300 psi exceed most standard concrete,
although high strength concrete is available now that substantially
exceeds this value. And this falls FAR short of even standard A36 steel.

http://www.harvel.com/piping-clear-pvc.asp
8300 psi? I come up with more like 37,500 psi since this was 4" dia sch
40 PVC pipe with no filling i.e. 60,000# load on something like 1.6
square inches of PVC total.
Material properties don't depend on the size of the pipe. Did you even
open the reference I provided? Do you understand MATERIAL properties?

Matt


Do you understand that under testing in my 50T press, it took a load of
~37,500 PSI on the 1' length of 4" sch 40 PVC pipe before it failed?
Material properties are irrelevant, that was the actual result of the
test I noted.


37,500 psi is a pressure, not a load.


It is both.

Material properties are not only
relevant, they are essential to almost all structural engineering
calculations (I know as I have a masters in civil/structural).


And what I presented was not a structural engineering calculation it was
simply the results of a real world test that point out that sch 40 PVC
pipe is a lot stronger than most people think.

And the
behavior of a short column is MUCH different than a long column. Ever
heard of Euler?


No kidding, and again, I didn't present any structural engineering info,
simply actual results of a real world test showing the surprising
strength of PVC pipe.


A nearly pure compression test (which is what a 1' long 4" pipe
comprises) has almost no relevance to the case of a column that has a
substantially different slenderness ratio and thus subject to a buckling
failure mode as well as possible bending moments due to eccentric loading.


Right, but again, I didn't present anything to the contrary. I indicated
that code approved PVC pipe based deck supports were available, which
they are, and an example showing that PVC pipe is stronger than people
think.


I didn't see a column length in the OP, but when "basement" is the
description rather than "crawl space" it is likely that the length is at
least 6' and possibly 8' or even more. This is far from being a 1'
column. Concrete filled PVC could work if sized properly, but using the
same size as the existing steel column is a fool's errand. Again, the
OP didn't mention the size of either the steel or the PVC, but I'll bet
there were likely nearly the same size. If that is the case, then the
PVC is almost certainly inadequate, unless the steel column was grossly
oversized for the required load.


Probably, and I didn't suggest the OP's scenario was proper or safe. I
simply noted that "Using PVC for deck supports" as in the subject line
is possible and code approved if done properly, and not a "Disaster
waiting to happen" as was also in the subject line. Can't seem to find a
link to the product at the moment. Believe I read about it in Fine
Homebuilding or perhaps JLC.

CWatters[_3_] May 20th 08 09:39 PM

Disaster waiting to happen? Using PVC for deck supports???
 

wrote in message
...
On Sun, 18 May 2008 18:28:48 -0400, Matt Whiting wrote:

Thomas G. Marshall wrote:
said something like:

...[snip]...


The concrete in steel lolly columns is to help keep them from
collapsing in a fire.

....so the preventing a dent thing is secondary, or not a concern...?



No, preventing buckling is a significant advantage provided by filling a
steel column.

Matt


Uh, yes. And the buckling it prevents would be the result of fire. Filling
the
columns with cement is to protect the columns from buckling in a FIRE.



PVC burns doesn't it?



CJT May 20th 08 09:40 PM

Disaster waiting to happen? Using PVC for deck supports???
 
CWatters wrote:

wrote in message
...

On Sun, 18 May 2008 18:28:48 -0400, Matt Whiting wrote:


Thomas G. Marshall wrote:

said something like:

...[snip]...



The concrete in steel lolly columns is to help keep them from
collapsing in a fire.

....so the preventing a dent thing is secondary, or not a concern...?



No, preventing buckling is a significant advantage provided by filling a
steel column.

Matt


Uh, yes. And the buckling it prevents would be the result of fire. Filling
the
columns with cement is to protect the columns from buckling in a FIRE.




PVC burns doesn't it?


So does steel.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

CWatters[_3_] May 20th 08 09:41 PM

Disaster waiting to happen? Using PVC for deck supports???
 

"Thomas G. Marshall" . com
wrote in message news: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).


For what?




[email protected] May 20th 08 09:48 PM

Disaster waiting to happen? Using PVC for deck supports???
 
On May 20, 3:40*pm, CJT wrote:
CWatters wrote:
wrote in message
.. .


On Sun, 18 May 2008 18:28:48 -0400, Matt Whiting wrote:


Thomas G. Marshall wrote:


said something like:


...[snip]...


The concrete in steel lolly columns is to help keep them from
collapsing in a fire.


....so the preventing a dent thing is secondary, or not a concern...?


No, preventing buckling is a significant advantage provided by filling a
steel column.


Matt


Uh, yes. And the buckling it prevents would be the result of fire. Filling
the
columns with cement is to protect the columns from buckling in a FIRE.


PVC burns doesn't it?


So does steel.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. *Our true address is of the form .- Hide quoted text -

- Show quoted text -


Steel burns? I guess I learned something new today.

JoeSpareBedroom May 20th 08 09:53 PM

Disaster waiting to happen? Using PVC for deck supports???
 
wrote in message
...
On May 20, 3:40 pm, CJT wrote:
CWatters wrote:
wrote in message
.. .


On Sun, 18 May 2008 18:28:48 -0400, Matt Whiting
wrote:


Thomas G. Marshall wrote:


said something like:


...[snip]...


The concrete in steel lolly columns is to help keep them from
collapsing in a fire.


....so the preventing a dent thing is secondary, or not a concern...?


No, preventing buckling is a significant advantage provided by filling
a
steel column.


Matt


Uh, yes. And the buckling it prevents would be the result of fire.
Filling
the
columns with cement is to protect the columns from buckling in a FIRE.


PVC burns doesn't it?


So does steel.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .- Hide
quoted text -

- Show quoted text -


Steel burns? I guess I learned something new today.

============

Anything will burn at the right temp.



[email protected] May 20th 08 11:44 PM

Disaster waiting to happen? Using PVC for deck supports???
 
On May 20, 3:53*pm, "JoeSpareBedroom" wrote:
wrote in message

...
On May 20, 3:40 pm, CJT wrote:





CWatters wrote:
wrote in message
.. .


On Sun, 18 May 2008 18:28:48 -0400, Matt Whiting
wrote:


Thomas G. Marshall wrote:


said something like:


...[snip]...


The concrete in steel lolly columns is to help keep them from
collapsing in a fire.


....so the preventing a dent thing is secondary, or not a concern...?


No, preventing buckling is a significant advantage provided by filling
a
steel column.


Matt


Uh, yes. And the buckling it prevents would be the result of fire.
Filling
the
columns with cement is to protect the columns from buckling in a FIRE.


PVC burns doesn't it?


So does steel.


--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .- Hide
quoted text -


- Show quoted text -


Steel burns? I guess I learned something new today.

============

Anything will burn at the right temp.- Hide quoted text -

- Show quoted text -


So there's no difference between burning and melting?

CJT May 21st 08 12:07 AM

Disaster waiting to happen? Using PVC for deck supports???
 
wrote:

On May 20, 3:53 pm, "JoeSpareBedroom" wrote:

wrote in message

...
On May 20, 3:40 pm, CJT wrote:






CWatters wrote:

wrote in message
m...


On Sun, 18 May 2008 18:28:48 -0400, Matt Whiting
wrote:


Thomas G. Marshall wrote:


said something like:


...[snip]...


The concrete in steel lolly columns is to help keep them from
collapsing in a fire.


....so the preventing a dent thing is secondary, or not a concern...?


No, preventing buckling is a significant advantage provided by filling
a
steel column.


Matt


Uh, yes. And the buckling it prevents would be the result of fire.
Filling
the
columns with cement is to protect the columns from buckling in a FIRE.


PVC burns doesn't it?


So does steel.


--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .- Hide
quoted text -


- Show quoted text -


Steel burns? I guess I learned something new today.

============

Anything will burn at the right temp.- Hide quoted text -

- Show quoted text -



So there's no difference between burning and melting?


Sure there is. Steel will do either (or both) depending on the conditions.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

HerHusband May 21st 08 04:44 PM

Disaster waiting to happen? Using PVC for deck supports???
 
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 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.


First, I'm no engineer, but a few thoughts did come to mind...

You didn't mention the height of the deck or the span between support
posts, but in general there shouldn't be much of a load on a deck (no
walls, ceilings, roofing, etc.). Assuming a typical residential
situation, of course.

If the post footings are below the frostline in the area, they shouldn't
heave anyway should they? But even so, PVC is fairly flexible, and even
concrete flexes a small amount. With "typical" structural movements, I
don't see this being an issue. They're not gonna "snap like twigs" at the
first sign of stress.

If the PVC is filled with concrete, I don't see why it would be any
different than a cardboard sonotube, except you would not need to remove
the PVC after the pour. Even if the PVC doesn't offer any structural
support, the concrete piers inside the PVC should support the weight of
the deck.

If you're concerned about "flex" in the column, you should install rebar
reinforcement whether you're using PVC, a sonotube, or even building a
square box for the concrete pier.

Unless this is a second story deck, or one perched out over a hillside,
"most" decks only sit a foot or two off the ground and are supported by
multiple pier posts. I doubt there will be any significant sideways loads
to buckle the columns.

A recent article in Fine Homebuilding showed a system that used PVC pipe
to support a small shed (with no concrete). If it works for a shed, it's
bound to be adequate for a deck.

Unlike a steel post, PVC won't rust. However, regular PVC will be damaged
by ultraviolet light from the sun, and will get brittle. You could avoid
this by using grey PVC conduit which has protection against ultraviolet
light.

Around here, many decks are built with nothing more than a 4x4 post
sitting in precast concrete pier blocks sitting on the ground and have
lasted for decades. Also, many mobile homes sit on concrete blocks that
are just dry stacked piers with no reinforcement (ours was setup that way
for 13 years, with one end nearly four feet off the ground, and we
survived two earthquakes with no problems). These are obviously UNDER
engineered situations, but it's also possible to OVER engineer the
support for a deck as well...

Anthony

scrumble[_2_] May 21st 08 08:45 PM

Disaster waiting to happen? Using PVC for deck supports???
 
Thomas G. Marshall wrote:
RicodJour said something like:
On May 18, 8:45 pm, wrote:
On Sun, 18 May 2008 18:28:48 -0400, Matt Whiting
wrote:
Thomas G. Marshall wrote:
said something like:
The concrete in steel lolly columns is to help keep them from
collapsing in a fire.
....so the preventing a dent thing is secondary, or not a
concern...?
No, preventing buckling is a significant advantage provided by
filling a steel column.
Uh, yes. And the buckling it prevents would be the result of fire.
Filling the columns with cement is to protect the columns from
buckling in a FIRE.

In a wood framed building? I guess if the fire started at the base of
the column that might be a good argument, but in any real situation
the house would be engulfed in flames long before the plastic
temperature of the steel was reached.

The concrete fill is to prevent buckling, partially from being dented,
but also to prevent localized failure which can occur at lower loads
than the straight compressive strength of the material(s) would
indicate.aconcern, though secondary,

only because the plasticity of steel could never be reached in a basement
without the rest of the house already having been reduced to dust. Or so it
seems to me. {shrug}


The problem with fire and steel beams/columns isn't so much from
structural weakness when the steel becomes hot, although that would be a
concern where the intention is to contain the fire for a length of time,
but more from the actual expansion of the steel, either from it pushing
other structural elements, or itself buckling when the expansion at both
ends is restricted.


--
scrum

(\_/) Procrastinator bunny says:
( . .) "I'll conquer the internets tomorrow"
C(")(")


All times are GMT +1. The time now is 03:22 PM.

Powered by vBulletin® Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004 - 2014 DIYbanter