The degree of kinematic indeterminacy of a plane structure shown in the figure neglecting axial strain, is
The degree of kinematic indeterminacy of a plane structure shown in the figure neglecting axial strain, is Correct Answer 7
Concept:
Kinematic indeterminacy (DK ) also known as degree of freedom.
Kinematic indeterminacy: The number of unknown joint displacement is called the degree of freedom.
|
Type of joint
|
Degree of freedom
|
|
Rigid Joint of plane frame |
3 (δ x , δ y , θ )
|
|
Rigid joint of a space frame
|
6 (3 rotation θ xy , θ yz , θ xz 3 translations δ x , δ y , δ z ) |
|
Pin joint of a plane frame (2D Truss)
|
2 (δ x , δ y ) |
|
Pin joint of a space frame (3 D Truss) |
3 (δ x , δ y , δ z ) |
|
Hinge joint
|
1 (θ ) |
|
Roller joint
|
2 (δ x , θ ) |
|
Fixed joint
|
0 |
NOTE: Neglecting axial strain.
When Axial deformations are neglected then
Dk = total degree of freedom - number of members
Calculation:
For the given 2D frame
Number of members = 6.
Number of rigid joints = 4, One fixed joint, and One hinge joint.
∴ DK = 4 × (3) + 1 × (1) + 1 × (0)
= 13
This is the total degree of freedom but the question asked is to neglect axial constraints
So our Dk = total degree of freedom - number of members.
= 13 – 6 = 7.