In my early civil engineering studies, I learned that ropes can only absorb tension but not compression because they are basically an infinite chain of hinges.
I can’t quite remember anymore how arches work, all I know is they behave in the opposite of ropes.
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You are right that the traditional arch construction made by stacking rocks without any binders only handle compression but not tension. Rocks in general do not handle tension very well and when you do not bind them together they do not handle any tension. So you can collapse an arch bridge by lifting it just slightly, there have been a number of accidents like this when the loading gauge have been exceeded.
However an arch does become stronger in tension once you start adding binders between the rocks or even rebar. This is fairly common in modern concrete bridges where they make the deck arched because just as rocks concrete also handles compression better then tension, but then add rebar to the bridge elements to handle tension loads as well.
Arches are architectural structures that excel at absorbing compression forces but are not well-suited to handle tension forces. This is because arches are designed with a curved shape that allows the force of gravity to be channeled down to the ground, effectively compressing the arch’s constituent materials (e.g., stone or brick) together. In contrast, tension forces tend to pull materials apart, which is not a natural load-bearing configuration for arches. To resist tension, additional structural elements like ties or cables are needed, as seen in structures like suspension bridges.
if you hang a chain between two points you get an arch in tension, if you make the same shape upside down you get an arch in compresssion
You needed a class to learn ropes dont take compression?
The shortest distance between two points is a line.
Imagine a totally flat beam supporting something heavy. It bows. The line has become a curve, so it is stretching in tension.
In an arch, you already have a curve but this time the force is pushing it from a curve into a line. This time the longer arch is being compressed into a shorter line.
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