The Catenary Arch
A 'catenary arch' is the curve a hanging flexible wire or chain assumes when supported at its ends and acted upon by a uniform gravitational force.
It is very close to a parabolic curve. Apparently it is the strongest of arch shapes.
Hanging a chain is a great way to figure out the shape of this kind of curve if your building a dry stone arch as long as you are planning to build it upside down.
The word catenary is derived from the Latin word for "chain." The curve is also called the alysoid, funicular and chainette. My problem is that making a catenary curve using a chain gives you many different shapes depending on how sort the length of chain is. It looks like a narrow rounded gothic when the chain is a long loop. As it gets shorter it takes the form of different segmented arches and if it gets really short it becomes almost a straight line! Can anyone explain this?