In two-hinged arch, how many unknown forces exist?

In two-hinged arch, how many unknown forces exist? Correct Answer Four unknowns

Explanation:

Three hinge arch :

  • In the case of a three-hinged arch, we have three hinges, two at the support and one at the crown and there are four reaction components in the three-hinged arch.
  • One more equation is required in addition to three equations of static equilibrium for evaluating the four reaction components.
  • Taking moment about the hinge of all the forces acting on either side of the hinge can set up the required equation, making 3  hinge arch determinate.

Two hinge arch :

  • In the two hinge arch, we have 2 hinges at two support of the arch and have four reaction or unknown components, as in a 3 hinge arch.
  • But here we don't have an additional equation to solve the structure and hence our 2 hinge arch is indeterminate by degree 1.

​Hinge less/ Fixed arch :

  • In the fixed arch, both the support are fixed. So, in a fixed arch six reaction forces ( One moment extra on each support ).
  • But, we have only 3 equilibrium equations. So, the degree of indeterminacy of fixed arch becomes 6 - 3 = 3. 

​[ alt="F1 Abhayraj Anil 05.02.21 D2" src="//storage.googleapis.com/tb-img/production/21/02/F1_Abhayraj_Anil_05.02.21_D2.png" style="width: 379px; height: 223px;">​

Related Questions

The most economical central angle of the arch rings of an arch dam can be adopted only at one place preferably at mid-height in an arch dam is of the type __________________