u/Fun_Curve_6727

can someone verify my calculations please? i'm a bit confused, thank you

my methodology:

n = no of members, r = no of reactions, j = no of joints, c = sum of [no of members meeting at a hinge - 1]

D of frames = 3n + r - 3j - c

D of trusses = n + r - 2j

pic 1 above

top left:

frame, n=2, r=3, j=3, c=0

D = 3*2 + 3 - 3*3 = 0, stable determinate

top right:

truss, n=14, r=4, j=10

D = 14 + 4 - 2*10 = -2, unstable

bottom left:

truss, n=10 r=4 j=7 c=13

D = 3*10 + 4 - 3*7 - 13 = 0, stable determinate

bottom right:

frame, n=5, r=6, j=5, c=3

D = 3*5 + 6 - 3*5 - 3 = 3, stable indeterminate

pic 2 above

truss, n=21 r=4 j=10

D = 21 + 4 = 2*10 = 5, stable indeterminate