Slope Deflection Method MCQ with answer and solution

Concept

Portal frames with or without lateral loads can be analyzed using classical displacement methods like slope-deflection and moment distribution, provided the sidesway effect is properly accounted for.

Step-by-step solution

1. Identify the degrees of freedom of the portal frame, including both rotational and translational (sidesway) degrees of freedom. 2. Apply the slope-deflection equations or moment distribution method (with sidesway correction) to solve for unknown joint displacements and moments. 3. Conclude that both methods are fully capable of analyzing such frames.

Explanation

A portal frame subjected to lateral loads undergoes sidesway along with rotation of joints. Both the slope-deflection and moment distribution methods are displacement-based matrix/iterative methods that can fully account for joint rotations and translational degrees of freedom (sidesway), allowing complete analysis of the frame.

Why the other options are wrong

A: Slope-deflection can handle lateral loads via sidesway equations. B: Moment distribution can handle lateral loads using the story-shear/sidesway correction technique. C: Both methods are actually capable of analyzing portal frames with lateral loads.

Shortcut

Remember that classical displacement methods (Slope-Deflection and Moment Distribution) can solve any statically indeterminate structure by considering both joint rotations and relative translations (sidesway).

Common mistake

Assuming that lateral loads cause un-analyzable conditions in moment distribution without realizing that sidesway can be handled using dummy lateral loads or correction factors.