The "Unit Load Method" used for calculating deflections in structures is an application of which fundamental principle?
- APrinciple of Superposition
- BPrinciple of Virtual WorkCorrect
- CCastigliano’s Second Theorem
- DEuler-Bernoulli Hypothesis
Solution
Concept
Unit Load Method and Principle of Virtual Work
Formula
N/A
Step-by-step solution
1. Read the question to identify the fundamental principle behind the "Unit Load Method" used in structural analysis. 2. Recall that the Unit Load Method applies a dummy (virtual) unit load to find deflections, which is an application of the Principle of Virtual Work. 3. Match this principle with the given options and select Option (b) as the correct answer.
Explanation
The "Unit Load Method" is based on the Principle of Virtual Work. It calculates actual deflections by applying an imaginary (virtual) unit load to the structure and equating external virtual work to internal virtual strain energy.
Shortcut
To remember that the Unit Load Method is based on the Principle of Virtual Work, use the association "Unit = Virtual": - Unit Load: Applies an imaginary (Virtual) unit load to find deflections. - Virtual Work: Equates external virtual work to internal virtual strain energy.
Common mistake
A common mistake is selecting option C (Castigliano’s Second Theorem) because students frequently confuse it with the Unit Load Method, as both are popular techniques for finding deflections. Another common mistake is selecting option A (Principle of Superposition) by confusing the basic assumption of linear elastic behavior with the governing energy principle. In reality, the Unit Load Method specifically derives from the Principle of Virtual Work by applying a dummy virtual load.
Correct answer: B) Principle of Virtual Work