The Point of contra flexure is a point where:
- AShear force changes sign
- BBending moment changes signCorrect
- CShear force is maximum
- DBending moment is maximum
Solution
Concept
Definition of point of contraflexure
Formula
NONE
Step-by-step solution
1. The point of contraflexure occurs along a beam subjected to bending. 2. At this point, the bending moment diagram passes through zero and changes sign from positive to negative or vice versa. 3. Consequently, the curvature of the beam changes sign at this point. Answer: B
Explanation
The point of contraflexure is defined as the location along a beam where the bending moment curvature transitions between sagging and hogging, passing through zero. Consequently, it is the exact position where the bending moment changes its algebraic sign.
Why the other options are wrong
A) The point where shear force changes sign corresponds to a maximum or minimum bending moment. C) Maximum shear force occurs at support locations or concentrated load points. D) Maximum bending moment occurs where shear force is zero or changes sign.
Shortcut
Point of contraflexure is where the bending moment changes sign (crosses zero).
Common mistake
Confusing the point where bending moment changes sign with the point where shear force changes sign or becomes zero.
Correct answer: B) Bending moment changes sign