What are the formulaes to calculate degree of indeterminancy?

 Following  are the formulas for the degree of indeterminacy for various structures

1. Two-Dimensional Jointed Truss (2D Truss):

   $$D_i = (m + r) - 2j$$
   

2. Two-Dimensional Rigid Frames (2D Frame):

   $$D_i = (3m + r) - 3j$$
   

3. Three-Dimensional Space Truss (3D Truss):

   $$D_i = (m + r) - 3j$$
   

4. Three-Dimensional Space Frame (3D Frame):

   $$D_i = (6m + r) - 6j$$
   

Where:

• $\mathrm{<span\; style="font-family:\; Cambria;\; font-size:\; medium;">m\; =\; number\; of\; members</span>}$
• $r$ = number of reactions
• $j$ = number of joints