A singly-bay single-storeyed portal frame ABCD is fixed at A and D as shown in the figure. If axial deformation is neglected, the kinematic indeterminacy is
A singly-bay single-storeyed portal frame ABCD is fixed at A and D as shown in the figure. If axial deformation is neglected, the kinematic indeterminacy is Correct Answer 3
Concept:
Static Indeterminacy: If the equilibrium equations are enough to analyze for unknown reactions, the structure is said to be statically indeterminate.
Ds = Dse + Dsi
Dse = r – S
Dsi = 3 × Number of closed loop (For portal frame)
Dsi = m- 2j+ 3 (For truss structure)
Kinematic Indeterminacy: It is the total number of possible degree of freedom of all the joints.
Dk = 3J - r (For portal frame)
Dk = 2J-r (For truss structure)
where, Dse = External Indeterminacy, Dsi = Internal Indeterminacy, Dk = Kinematic Indeterminacy, r = No. of unknown reactions, S = No. of equilibrium equation, m = No. of mombers & J = No. of joints
Solution:
∴ Dk = 3j - r = 12 - 6 = 6
For axial deformation is neglected, Dk = 6 - 3 = 3