Linear
Parabolic
Constant moment for all curvatures
Constant curvature for all moments
Answer is Right!
Answer is Wrong!
The correct answer is B. Parabolic.
A plastic hinge is a point in a structure where the bending moment is large enough to cause the material to yield plastically. This results in a loss of stiffness, and the structure can no longer carry the same load. The moment-curvature relation at a plastic hinge is parabolic, which means that the moment increases with the square of the curvature. This is because the plastic deformation of the material is non-linear.
Option A is incorrect because the moment-curvature relation is not linear. Option C is incorrect because the moment is not constant for all curvatures. Option D is incorrect because the curvature is not constant for all moments.