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Vault Collapse ? - Forno Bravo Forum: The Wood-Fired Oven Community

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Vault Collapse ?

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  • Vault Collapse ?

    Does anyone have any first hand experience of a fully cured, completed, well used oven having the vaults collapse? Not just in the construction phase?

    I now know of at least 3 ovens, mine, Tscarborough's and Craig's that are at least some form of vault and have not heard of any problems.

    Mine has been just fine for the last year+, the question came to me after I read a few posts a little critical of the vault design because of that possibility.

    Derk

  • #2
    Re: Vault Collapse ?

    My vault is just fine.
    The possibility of a properly constructed vault collapsing are about the same as a domed oven collapsing.

    As with any arched structure there are precautions against collapse that have to be built into the arch.

    Same goes for a dome.
    The English language was invented by people who couldnt spell.

    My Build.

    Books.

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    • #3
      Re: Vault Collapse ?

      The possibility of a properly constructed vault collapsing are about the same as a domed oven collapsing
      Vault/dome design hasn't really changed since the ancient ovens were built and many of them are still standing. Today's refractory building materials and cutting tools are so good it would be difficult to have an oven collapse if constructed properly.

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      • #4
        Re: Vault Collapse ?

        Built correctly, neither will fail, built poorly either may fail.

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        • #5
          Re: Vault Collapse ?

          Hi Tom, hope you are having a merry Christmas, my vault is just fine, thought I would just ask. I am planning on it being my mausoleum after I die, light a fire, throw me in and brick up the door.

          Derk

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          • #6
            Re: Vault Collapse ?

            A late addition. A dome will have roughly half the stress of a vault, all other things being equal (thickness, width/diameter, etc.) That's actually for an equal pressure model, in a gravity model it's closer to 2/5. There is a reason dome shapes are used so much.

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            • #7
              Re: Vault Collapse ?

              The bigger the r (flatter the vault) the greater the sideways thrust on the top of the walls.
              Kindled with zeal and fired with passion.

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              • #8
                Re: Vault Collapse ?

                There is a very interesting analysis (with calculations) regarding the comparative strengths of arches, vaults and domes here:

                Auroville Earth Institute

                The author states that the circular forces combined with line of thrust creates a net of compression forces distributed over the entire surface of the dome, which can resist tremendous stress.

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                • #9
                  Re: Vault Collapse ?

                  Absolutely true, but for any given r value the vault still has 2 to 2.5 times the stress of a dome with the same cross section.

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                  • #10
                    Re: Vault Collapse ?

                    Also the end walls of a barrel vault should be inside/under the vault to prevent the expanding vault pushing them out. If the end walls are outside/beside the vault they should have steel bracing. This is standard practice for kilns of this configuration which undergo way more expansion and stress, but the principle still applies to a WFO.
                    Kindled with zeal and fired with passion.

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