If the arc is pinned on rollers, for example, just two supports at it ends?

Answer 1

Good, you try to explain. But it is not possible to provide Roller supports at both the ends in arch, and specially when the supports are provided at two ends only and no hinge at crown, both the ends of arc should be Hinged(pinned) only. This is an indeterminate structure.

Now here both: Vertical reactions and Horizontal thrust are required to be found out. But the analysis is easier as if supports do not yield, displacement is zero in both the directions.

Now if supports yield, then we need to know the amount by which the horizontal displacement takes place, then only we can find horizontal thrust(reaction).

Here we can obtain vertical reactions by using conditions of equilibrium.

Well, this is very general answer, there are different methods for the analysis of different arches, if you write the specific problem, i would be pleased to solve it for you.

And, most students, i have seen, do not attend to Arches' problems, so i am happy you are sincerely trying to understand this analysis.

Good luck.

Answer 2

Yes, that's just two supports on its ends, but because they are rollers, they can't resist moments or force in the direction that would cause the rigid body to roll

Answer 3

???
I give up. Is there a question in there somewhere that I'm just too stupid to recognise?

Doug

Answer 4

Are you sure this shouldn't be in the hairdressing section?