Answer & Solution
Answer: Option C
Solution:
To determine the degree of static indeterminacy (Ds) for a rigid-jointed plane frame, use the formula:
Ds = (3m + R) - (3j + A)
where:
m = number of members,
R = number of reaction components,
j = number of joints,
A = number of internal hinges (A = 0 in this case).
Given:
m = 15 (members),
R = 3 (reaction components),
j = 14 (joints),
A = 0 (no internal hinges).
Substitute these values into the formula:
Ds = (3 * 15 + 3) - (3 * 14 + 0)
Ds = (45 + 3) - (42)
Ds = 48 - 42 = 6
Thus, the degree of static indeterminacy is 6.