Which would be stronger?

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nrcarter

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I know that an arch is considered to be the strongest when weight is applied from the outside inward via the extrados however what about inside outward via the intrados? Which (circle, arch or ellipse) would be the strongest this way? Thanks!
 
nrcarter said:
I know that an arch is considered to be the strongest when weight is applied from the outside inward via the extrados however what about inside outward via the intrados? Which (circle, arch or ellipse) would be the strongest this way? Thanks!
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Please post the EXACT problem as it was presented to you including any figure/s that was supplied with the question. Include your thoughts (what do you think the answer ought to be).
 
This isn't a problem that was presented to me, however it is a problem I am needing to solve. The only factors I can think of would be that the ellipse and the circle would only be a half (the ellipse would be half the longest way) and an arch is already considered a half and all having the same length base. Sorry that this isn't written in mathspeak but I appreciate the effort!
 
I had to look up the words extrados and intrados, which I had never seen.

Why is this a math question? What is the context? Why are you asking?
 
I have searched for the answer on my own but cannot seem to find any clear answers. The context is an invention in which weight would be pushing from the inside outward against the intrados in a centrifugal fashion. The difference in shape may sound like a minor detail and it may well be but I would prefer to know which are stronger or weaker and why.
 
If we assume that masonry's weakness to tension is the main culprit, because strength to compression is what makes an arch work,
then we want the shape that minimizes the tension in the "arch" as force is uniformly applied from the "interior" of the "arch".

Intuitively a straight line is going to zero out any tension in the "arch/wall" but that's not going to provide a very useful shape.

Basically you want to minimize the curvature of your "arch" subject to the constraint that it still provides a useful shape.

One thing you might do is use a fairly eccentric horizontal ellipse and reinforce the ends with additional masonry.
This provides additional support where the tensile forces are greatest.
 
I understand what you are saying however this isn't a masonry specific question. I understand the answer could be skewed because of materials used in making the shapes in question. I am just looking for more general answers and why whether its made with steel, masonry or plastic. I also understand that an arch can technically be half of a circle but I am more focused on the arch itself even if it doesn't connect with its vertical part of the structure.
 
nrcarter said:
I understand what you are saying however this isn't a masonry specific question. I understand the answer could be skewed because of materials used in making the shapes in question. I am just looking for more general answers and why whether its made with steel, masonry or plastic. I also understand that an arch can technically be half of a circle but I am more focused on the arch itself even if it doesn't connect with its vertical part of the structure.
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Can you provide us with a sketch of loading on the structure?

Make sure that you are satisfying condition of static equilibrium in your sketch.
 
I don't have a sketch at the moment...I was trying to figure out this problem before making one.
 
nrcarter said:
I don't have a sketch at the moment...I was trying to figure out this problem before making one.
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You - I suspect - are playing a bit coy!!

So if this is an analysis for an invention, would you include us as contributor to your patent application?
 
I have not been coy about a thing...I asked my questions as straightforward as I can in layman terms as I know and I have been honest in everything. Its not an analysis but a question just like asking if concrete is stronger than asphalt and why. I am getting the feeling however that no one knows the answer to my question. If I was to include this site as a contributor I would have to add google, ustpo and any other sites I have gleaned public information from as well as the many books I have looked into at the library. Besides...isn't the site called freemathhelp.com? Not freemathhelpunlesswecangetsomerecognition.com...Just asking...
 
nrcarter said:
I have not been coy about a thing...I asked my questions as straightforward as I can in layman terms as I know and I have been honest in everything. Its not an analysis but a question just like asking if concrete is stronger than asphalt and why. I am getting the feeling however that no one knows the answer to my question. If I was to include this site as a contributor I would have to add google, ustpo and any other sites I have gleaned public information from as well as the many books I have looked into at the library. Besides...isn't the site called freemathhelp.com? Not freemathhelpunlesswecangetsomerecognition.com...Just asking...
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yes - for questions involving commercial endeavor! - Just telling....
 
You are way ahead of yourself...between your mentioning patent applications and commercial endeavors...I'm just trying to figure out a problem and figured maybe people that are supposed to help answer questions "free" may be a help...maybe I was wrong in assuming this due to the site name?
 
I think this question is just outside of the domain of the site, as it hasn't been reduced to a math question. Sometimes people here are able to help with engineering issues, but if not ... I guess you have to go to FreeArchDesignHelp.
 
Good one! I appreciate the time put forth towards my question. ?? (Rock On & Live Long And Prosper)
 
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