Energy Methods MCQ with answer and solution

Concept

Fundamental distinction between force and displacement methods of structural analysis based on their primary unknowns.

Step-by-step solution

1. Identify the two primary approaches in classical and matrix structural analysis: Force Method and Displacement Method. 2. In the Force Method (Compatibility Method), the basic unknowns are forces (redundant reactions or internal forces). 3. In the Displacement Method (Equilibrium Method), the basic unknowns are joint displacements (rotations and translations). 4. Match these definitions to the respective order in the question: Displacement method -> Displacements, Force method -> Forces.

Explanation

In structural analysis, methods are broadly classified into two categories based on their basic unknowns. The displacement method (such as Slope-Deflection, Moment Distribution, and Stiffness Matrix method) uses joint displacements as basic unknowns. The force method (such as Flexibility Matrix method, Consistent Deformation method, and Castigliano's theorem) uses redundant forces as basic unknowns.

Why the other options are wrong

B: Reverses the basic unknowns for the two methods. C: Both cannot be displacements. D: Both cannot be forces.

Shortcut

Remember 'Displacement method = Displacements (stiffness)' and 'Force method = Forces (flexibility)'.

Common mistake

Reversing the order of unknowns since the question lists 'displacement method' first and 'force method' second, but options might list them as forces and displacements.