Question

The equation for degree of static indeterminacy = (m + t) - 3j is true for which of the following frames, where m is the number of unknown member forces, r is unknown reaction components and j is the number of joints?
1. Rigid jointed space frame
2. Pin jointed plane frame
3. Rigid jointed plane frame
4. Pin jointed space frame

Answer 1

Correct Answer - Option 4 : Pin jointed space frame

Concepts:

 The static indeterminacy for frames under different conditions are:

1. Pin Jointed space Frame (3D)

D_s = m + r - 3j

2. Pin Jointed Plane Frame (2D)

D_s = m + r - 2j

 3. Rigid Jointed Plane Frame (2D):

D_S = 3m + r - 3j - R;

4. Rigid Jointed Space Frame (3D):

D_S = 6m + r - 6j - 3R;

Where,

m is the no of members

r is no. of support reactions

R is total no. of releases

J is the nos. of joints