Three-Hinged Arch
Three-hinged arches are statically determinate and can be analyzed by separating the two members and applying the equations of equilibrium to each member.

Exemple :
The three-hinged open-spandrel arch bridge like the one shown in the photo has a parabolic shape. If this arch were to support a uniform load and have the dimensions shown in Figure a, show that the arch is subjected only to axial compression at any intermediate point such as point D. Assume the load is uniformly transmitted to the arch ribs.

