Can this structure stand without internal support?

Discussion in 'Architecture & Engineering' started by Oystein, Jan 30, 2017.

  1. DaveC426913 Valued Senior Member

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    See post 12. Arches certainly do stand on their own. Andy Goldsworthy has made a a coffee table book showing it can be done.

    But this arch is much taller and more delicate than AG's arches, so that is a little odd, though still not totally implausible.

    But - considering we are all pretty certain the bottom arch cannot stand without support, it is quite reasonable to suppose that they used support on the top half as well. (why bother faking only half of a magic trick?)
     
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  3. Oystein Registered Senior Member

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    This structure cannot exist without support of glue or metal rods. Anyone who thinks this structure is free standing has no common sense. Period.
     
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  5. origin Trump is the best argument against a democracy. Valued Senior Member

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    I do not think a single person in this thread thought that structure could stand on its own.
     
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  7. billvon Valued Senior Member

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    Fortunately no one here thinks that.
     
  8. rpenner Fully Wired Staff Member

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    http://www.carlpeverall.com/Stone-Sculpture.html

     
  9. cluelusshusbund + Public Dilemma + Valued Senior Member

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    Its quite lovely... please give a link to whare it was bein discussed... mayb we can learn more about this particular piece of stone art work.!!!

    Edit:::

    Nevermind... rpenner found the art.!!!
     
  10. Woody1 Registered Senior Member

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    178
    The pile of rocks can not stand on its own. I cut it in half to show the free body diagram. All the forces are shown as they act on the body. In the vertical direction gravitational force Fg = Fv hence frictional force must be zero, and there is an unresolved coupling between Fv and Fg. Fh and R1 reaction forces point in the same direction since the structure is unsupported at the top. Hence the right half of the structure pushes to the right and it is bound to fall without glue... Even if the right half was one solid piece. It also slides down the slip plane. The arch could theoretically stand on its own above the horizontal rock with a round counterbalance rock, that is located midway up the hight.

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    Last edited: Jun 1, 2017
  11. Counter Registered Senior Member

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    Yes it's the annual stone-stacking championships. How can someone stack stones like that though? Their arms are not big enough!
     
  12. Woody1 Registered Senior Member

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    178
    Here's an even simpler diagram that makes it pretty clear that the right leg would rotate clockwise even if it was in one piece.

    On second thought, you have a point. If the bottom-most piece is counter-balanced to the left of the rotation point --- then it would be possible to have the leg remain erect. It all depends on the center of gravity for the right side. A good piece of lead might do it as a counterbalance weight behind the rock.

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    Last edited: Jun 2, 2017
  13. cluelusshusbund + Public Dilemma + Valued Senior Member

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    I tested the pitcher of the arch wit a chain an it apears to be a catenary arch.!!!

    https://en.wikipedia.org/wiki/Catenary_arch


    "The line of thrust is the locus of the points, through which forces pass in a retaining wall or an arch.
    It is the line, along which internal forces flow,
    In a stone structure, the line of thrust is a theoretical line that through the structure represents the path of the resultants of the compressive forces, For a structure to be stable, the line of thrust must lie entirely inside the structure"

    https://en.wikipedia.org/wiki/Line_of_thrust


    In Concluson:::

    Facts have changed my mind.!!!

    Sinse the upper half of the arch art-work apears to be a catenary arch... it could have a line of thrust that lies entirely inside the structure... so it is wit-in the realm of posibility for the upper arch to stand on its own.!!!
     
    Last edited: Jun 2, 2017
  14. timojin Valued Senior Member

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    I suppose the structure as is could stand , but the point is could you ansamble it stone after stone ?
     
  15. Woody1 Registered Senior Member

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    The upper half can work. It's the lower half that I'm looking at. I'm just going by eyeball. If the Center of gravity can come to the left of the rotation point at the foot, then I think you have it. You would need a retaining wall on both the sides of the entire structure, and the last stone to place would be the counterbalance stone at the right middle.
     
  16. exchemist Valued Senior Member

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    I just thought I ought to chip in at this point, to say that there is NO WAY the bottom half can possibly stand on its own without support or glue.

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  17. Woody1 Registered Senior Member

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    I think the analysis goes beyond what I've done. It can be modeled as 4 pieces, with 2 on the right and two on the left. When you say "glue" you are talking in terms of high frictional forces between the rocks. I don't know if the rocks have enough "sticking" force on their own in the slip planes.
     
  18. spidergoat Valued Senior Member

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    Please allow me to settle this issue permanently. Did a Google search of the picture and found the artist's website. He says this:

    "The Gift" incorporates the outstretched offering slab on the right which was intended to add gesture as well as relieve the symmetry of the oval. Probably the most challenging piece technically so far, it is assembled from eighty nine irregular stones which had to be cut and drilled to fit together with grace and continuity.

    Also this:
    My technique is simple. Stones are arranged in balance with minimal alteration to a point of resolve, then fixed permanently by invisibly drilling and anchoring with steel.

    http://www.carlpeverall.com/Stone-Sculpture.html

     
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  19. Woody1 Registered Senior Member

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    178
    Thanks spider, drilling and doweling is even stronger than glue.

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    Without permanent attachment -- the structure would be highly unstable even if it could stand for a few seconds.. Aren't you in architecture?
     
    Last edited: Jun 2, 2017
  20. timojin Valued Senior Member

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    Nice try , but this is different apple and orange
     
  21. Woody1 Registered Senior Member

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    Go to the link he provided and you'll find the identical picture. You have to scroll down to it.
     
  22. DaveC426913 Valued Senior Member

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    7,227
    Indeed. Woody is correct. It is imge #6.

    On the page the artist - several times in several ways - describes the cutting, drilling and fixation he employs in an effort to make the works permanent.

    Specifically for that work, he says: "Probably the most challenging piece technically so far, it is assembled from eighty nine irregular stones which had to be cut and drilled to fit together".
     
  23. spidergoat Valued Senior Member

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    Design.
     

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