A higher resolution image, from a slightly different viewpoint

The roof of the Persian Throne Room of the Taq-i-Kisra, now in Iraq, is the best surviving example of an ancient large span structure built to a catenary profile, the shape that will minimise bending moments in a structure of uniform thickness, standing under its own weight.

The red line added to the photograph is a catenary, and the blue line a parabola with the same span at first floor level. The plot suggests that the roof shape from first floor level does indeed approximate a catenary, although the low resolution photograph and irregular outline of the end face of the structure make it difficult to be certain.

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Looks like a cantenary on the inside and a parabola on the outter surface. Looks a bit like a bit of thickening in the structure at the base of the arch

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Hey

You’re not likely to check this anytime soon, but if you do, could you please email me the link of the second picture untouched, or it itself

its for a school add maths project

Hi Fisher

This is the link I used:

http://farm3.static.flickr.com/2106/2086914401_c693a8e3b0.jpg

Hope your project goes well.

If you are working on arches you might be interested in this post as well:

http://newtonexcelbach.wordpress.com/2009/06/16/elegant-proofs-4-the-optimum-shape-of-an-arch/

Thanks a lot, it’ll help a lot

Hey,

Just a minor correction, Taq-i-Kisra is in Iraq not Iran although it was named after a Persian emperor.

http://en.wikipedia.org/wiki/Taq-i_Kisra

Thanks Sam. I have corrected the text.