The number of independent displacement components at each joint of a rigid-jointed space frame is_______________?

A. stable and statically determinate
B. stable and statically indeterminate
C. unstable
D. none of the above
where m is number of members, r is reaction components and j is number of joints

i) of a stiffness matrix must be positive
ii) of a stiffness matrix must be negative
iii) of a flexibility matrix must be positive
iv) of a flexibility matrix must be negative
The correct answer is
A. (i) and (iii)
B. (ii) and (iii)
C. (i) and (iv)
D. (ii) and (iv)

A. 2
B. 3
C. 4
D. unrestricted

A. unstable
B. stable and statically determinate
C. stable and statically indeterminate
D. none of the above

A. slope
B. curvature
C. deflection
D. bending moment

A. 2j-r
B. 3j-r
C. j-2r
D. j-3r
where j is number of joints and r is reaction components