An arch can be treated as a curved beam

The influence line diagram for reaction at a support of a simply supported beam is

The influence line diagram for S.F. or B.M at a section is

The influence line diagram for reaction at the support of a cantilever will be a

Which load is obtained when equilibrium and mechanism conditions of plastic analysis are satisfied?

Three hinged arch will have three hinges

The equations of compatibility are written based on

The moment of inertia of square section is

The influence line diagram for shear force at a section on a cantilever will be