Timber Raised Pond Design

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Tony K
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Timber Raised Pond Design

Postby Tony K » Wed Oct 11, 2017 11:15 am

I'm building a raised timber pond for the garden and would appreciate some advice on the load bearing capability of the timber structure. The pond is 1.8m x 1.2m and 1.1m high, using 32mm thick, 140mm wide T&G timber and a PVC liner. The corners are notched and very tight with solid interlocking joints. It will hold 1650 litres of water.

I'm trying to work out the pressure on the structure walls and the load bearing capacity of the wood, and prove that the current design is up to it. Also, I wouldn't mind scaling up the design and would like to know how big I can go.

I've made a few calculations and have a good idea of the force on the walls due to hydrostatic pressure, I reckon it is 10.7 N/mm² (1.5psi). I can't figure out how to calculate the bending capability of the timber, it is C16 Grade T&G, 140mm wide. There seem to be plenty of span tables available but they're more concerned with load bearing joists taking the weight along the grain.

Cheers in advance.

JonR
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Re: Timber Raised Pond Design

Postby JonR » Sun Oct 15, 2017 10:05 am

I think I would over engineer it and use sleepers on edge or 6x3 Tan C24's and then clad it in T&G.

thatsnotafestool
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Re: Timber Raised Pond Design

Postby thatsnotafestool » Thu Nov 30, 2017 9:01 pm

Surely a side load from hydrostatic pressure is still a load. Same as a load bearing joist.

Or look at this

https://www.physicsforums.com/threads/l ... nk.581539/
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9fingers
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Re: Timber Raised Pond Design

Postby 9fingers » Fri Dec 01, 2017 8:20 am

Try using the sagulator. Each side of your pond could be considered as a shelf on its side?
Bob
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Tony K
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Re: Timber Raised Pond Design

Postby Tony K » Mon Dec 04, 2017 12:43 pm

thatsnotafestool wrote:Surely a side load from hydrostatic pressure is still a load. Same as a load bearing joist.

Or look at this

https://www.physicsforums.com/threads/l ... nk.581539/


You're right, hydrostatic pressure can be considered to be lateral force applied to the pond wall, I have calculated this, as detailed in the original post, in much the same way as your link advises.

The difference with joists is that the load is applied along the grain and all available stress tables take this into consideration.

Tony K
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Re: Timber Raised Pond Design

Postby Tony K » Mon Dec 04, 2017 12:44 pm

9fingers wrote:Try using the sagulator. Each side of your pond could be considered as a shelf on its side?
Bob

Sounds good, where can I find your mysterious sagulator?

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Re: Timber Raised Pond Design

Postby promhandicam » Tue Dec 05, 2017 10:59 pm

Tony K wrote:
9fingers wrote:Try using the sagulator. Each side of your pond could be considered as a shelf on its side?
Bob

Sounds good, where can I find your mysterious sagulator?

google

Tony K
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Re: Timber Raised Pond Design

Postby Tony K » Mon Dec 11, 2017 9:49 am

promhandicam wrote:
Tony K wrote:
9fingers wrote:Try using the sagulator. Each side of your pond could be considered as a shelf on its side?
Bob

Sounds good, where can I find your mysterious sagulator?

google


You're hilarious.

thatsnotafestool
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Re: Timber Raised Pond Design

Postby thatsnotafestool » Mon Dec 11, 2017 9:58 am

Tony K wrote:
promhandicam wrote:
Tony K wrote: Sounds good, where can I find your mysterious sagulator?

google


You're hilarious.


No, he isn't. Just being reasonable. You've been given the right word to search for. So...don't be lazy. JFDI.
The advantage of a bad memory is that one enjoys several times the same good things for the first time.
Friedrich Nietzsche


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