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Pvc pipe compression strength

by dr dodge
Tags: compression, pipe, strength
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dr dodge
#1
Jun23-10, 01:38 PM
P: 336
I have an "odd" use for pvc pipe. My house is made exclusively of styrofoam and plastic. (and a geodome to boot) I need to stick with this as any other material that was used has failed miserably (wood and steel mainly)

my question is, how much weight can a 10' piece of 3" schedule 40 support safely?

the internet has not provided useful info so far (it seems nobody else builds structural stuff with pvc pipe), and I figured I'd run it past ya'll

thanks,

dr
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Q_Goest
#2
Jun23-10, 02:14 PM
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Hi dr. Dodge. It all depends on how the pipe is being loaded. Imagine for example, a 10 foot long, 3" diam pipe cantilevered horizontally from a structure and hanging a load on the end. Compare that to the same pipe that's cantilevered vertically (like a flag pole) and putting the same load on it such that the pipe is now in compression instead of bending. How a pipe is supported (rigidly or loosely) and how it's loaded make a huge difference in how much load it can support. The only thing you can do is provide a drawing with all the information on it so people can do a proper stress analysis.
dr dodge
#3
Jun23-10, 02:21 PM
P: 336
the pipes will be straight up (flag pole like) and then will be bonded to the existing house with "great stuff" They will support an overhead panel also made from pvc/foam. there will be, for all practicle purposes, no bending loads, only vertical.

i can tell ya'll, I bought this house 10 years ago, and learning how to work on it has been interesting. I use elastomeric roof compound, and window screen, to make what I call "elasto-glass" (because the process is similar to laying fiberglass and resin)

dr

dr dodge
#4
Jun25-10, 01:07 PM
P: 336
Pvc pipe compression strength

ok, well never mind, then
I will just shoot this off the hip

dr
pantaz
#5
Jun26-10, 05:06 PM
P: 589
Filling the pipe with something will increase its load capacity. I would use concrete, but if you insist on restricting it to plastic type materials, I suppose two-part urethane foam would still be better than leaving them hollow. It would likely increase the insulating properties, also. Cost of the foam will be significant.
sardonicus
#6
Jun26-10, 05:59 PM
P: 46
Dr, How about some photo's, it sounds like an interesting house.

You can find an approximate number for it's buckling load using formula from Euler.

Buckling force F = pi^2 * E * I / L^2

I=3 in^4
E=400000 lbs / in^2
L = 120 in

You get 822 lbs, that's the buckling load. You'll want to back off 1/3, so about 500 lbs.

There are other limits, especially when the buckling length gets shorter (try L=12"). But for a 10 foot piece that should be pretty good.
dr dodge
#7
Jun28-10, 07:08 AM
P: 336
thanks, that helps. the panel I am going to install is less than 50 lbs at this time (not bad for a 13' x 10') I will be adding the centeral core of 1 1/2" thick styrofoam

I was mainly concerned with just the holding it up until we set it with the "great stuff" (I have to buy it a case at a time...lol

dr
pantaz
#8
Jun28-10, 04:07 PM
P: 589
Quote Quote by dr dodge View Post
I was mainly concerned with just the holding it up until we set it with the "great stuff" (I have to buy it a case at a time...lol

dr
Are you buying the individual cans? For your use, their "Froth-Pak" would be much more economical.

Other manufacturers offer similar products: http://www.google.com/products?q=spray+foam+insulation
sardonicus
#9
Jun28-10, 06:09 PM
P: 46
No pics? Any particular reason for a plastic and foam house? If it's really light uplift in high winds may be worth checking.
dr dodge
#10
Jul2-10, 06:32 AM
P: 336
I bought my house my house built like this already. It was designed and built by a ME as his dream house in 1989. It slowly degraded after he sold it and moved to michigan. then the guy that had it before me had spray ureathane blown over the whole thing and coated with elastomeric. The wall thickness is 8" of styrofoam, 1/4" concrete stucko, 1 1/2" of spray foam and elastomeric that is (now) aproaching 1/8 - 1/4" thick. 5 years ago I started to upgrade it with thermopane windows (replacing the singe pane ones) and removed the central A/C and moved to 3 window units in permant boxes in the walls above the new windows. I heat all winter long with a dehumidifyer and a halogen floor lamp. A/C went from a 20+ year old 5 ton unit to 2 - 1600 btu units and a single 3600 unit. All 120vac.

The sound inside does "very strange" things, but the coolest thing is when it rains hard, it sounds like ping pong balls hitting the outside. Almost every time I hear it I think of the old kids show, Capt Kangaroo, and the moose dropping the ping pong balls (oppps, dated myself) and crack up.

It has been a real learning experience, and I have done lots of experiments prior to deploying some kind of repair/improvement

I have aquired materials for the "carport from XXXX" (6 - 36 ft x 14" I beams) and hope by next year to have the frame assembly for solar water heating.

If anyone would want a tour, and you find yourself in the houston area, PM me, we'll drink a cold beverage or two, and I'll give ya the "free 50 cent tour"

I will try to get some pics of both the house and some of my "cored pvc/foam panels" to post later

thanks,

dr
sardonicus
#11
Jul3-10, 02:40 PM
P: 46
That is interesting dr. I vaguely recall Captain Kangaroo too, hah. If ever I go to Texas I will try to remember the foam house. S
KalamMekhar
#12
Jul3-10, 07:05 PM
P: 27
This seems like a very awesome house dr! PVC pipes are definitely able to handle a large load force by itself, but flexion is a problem. I have actually seen a PVC pipe crack with a heavy load on it (vertically loaded) when the smallest amount of horizontal force was applied to the pipe. As soon as PVC pipe starts to bend, it is drastically weaker.

The best idea would be to have a PVC pipe with a 1/2" re-bar reinforced concrete interior. 1 stick of 1/2" would be sufficient enough to reduce the flex of the concrete and the pipe, as long as the re-bar is properly anchored to the floor and the roof.
blimkie.k
#13
Jul5-10, 08:31 AM
P: 129
Sounds interesting but what are the pros and cons to having a house made entirely of plastic products. What makes it better from a traditional wood/concrete structure?

I can't see a house like this ever passing building inspection in Ontario, our codes are pretty strict. Not sure what they are like compared to Texas though.
dr dodge
#14
Jul6-10, 06:00 AM
P: 336
well, first advantage, eat this termites...lol
my house is so thermally tight that all winter I heat with a dehumififyer and a halogen floor lamp. even when we were in the 20-30's (F) last winter. the walls are a total of about 10" thick solid styrofoam or ureathane
I am in am "unrestricted" area which means no building codes.


brings up an interesting point though
did ya'll know that loans, insurance, and building codes are all "stacked against" non-conventional/ eco friendly/ high efficiency house construction. I subscribe to the newsletter from the monolithic dome people in Italy, TX and there have been some pretty good essay/articles on this.

something to seriously consider if you want to build/buy a super energy efficient, non conventional house.

dr


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