The degree of Kinematic Indeterminacy (Dk) for pin jointed space frame if members are extensible is:
Where, r = Number of reactions, j = Number of joints and m = Number of (members whole, extension is neglected.
1
Dk = [3j - r]
2
Dk = [2j - (m + r)]
3
Dk = [2j - r]
4
Dk = [6j - r]