Reason for parabolas in bridges?

[B.karthik]

Reason for presence of parabolas in sides of bridges like in Napier bridge in Chennai,India?

[admin]

Please ask the architecture!!!

[Haseeb Jamal]

Reason for presence of parabolas in sides of bridges like in Napier bridge in Chennai,India?
May be You can find your answer in the Bridge Tutorials available on the below link:

Bridge Construction and Design Video Tutorials (http://www.aboutcivil.com/bridge-design-construction-video-tutorials.html)

[Justin Kane]

The catenary arch or curve of cables transfers the load to the supports with the least amount of strain and thus the least material. When a bridge is flat beam or a truss, the material in the center of the bridge is bent down with a load and pulls sideways on the support piers. The beam/truss must handle all of that bending to keep from breaking. With an arch, the forces are transferred in different lines, allowing thinner material. But since it is trickier to build an arch and the curve underneath in particular may require that the top part be higher, etc. to get traffic underneath, it may be cheaper over all to put flat beams on upright piers and have a nice rectangular space under the bridge.