Question

In influence line diagrams (ILD):

• A. Points remain fixed, position of load changes
• B. Points change, position of loads remain fixed
• C. Both of them changes
• D. Neither of them changes

Hint:

Influence line diagrams are mainly used for structures subjected to moving loads such as bridges.

Answer 1

The Correct Option is A

Step 1: Understanding influence line diagrams.
An influence line diagram represents how a response function (reaction, shear force, bending moment, etc.) at a fixed point of a structure varies as a unit load moves across the structure.
Step 2: Key characteristic of ILD.
In ILD analysis:
- The structure and the point of interest remain fixed.
- Only the position of the load changes along the span.
Step 3: Analysis of options.
(A) Correct, because the load moves while the point remains fixed.
(B) Incorrect, points do not change in ILD.
(C) Incorrect, both do not change simultaneously.
(D) Incorrect, load position does change.
Step 4: Conclusion.
Hence, the correct answer is (A).