Question

Theory of simple bending equation is applicable for

• A. constant shear face and zero bending moment
• B. constant bending moment and zero shear force
• C. zero bending moment and zero shear force
• D. constant bending moment and constant shear force

Hint:

The ideal condition for the simple bending theory is called Pure Bending.
Pure Bending means:
- Bending Moment = Constant.
- Shear Force = Zero.
An example is the central portion of a beam loaded with two symmetric point loads.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
When is simple bending theory strictly applicable?

Step 2: Key Condition (Alternate):
Pure bending: no shear force, only constant bending moment. V=dM/dx=0 when M constant.

Step 3: Detailed Explanation:
Theory derived assuming plane sections remain plane, no shear distortion. This holds exactly when V=0. In practice, formula used even with shear, but errors are small for slender beams.

Step 4: Final Answer:
Constant bending moment and zero shear force (pure bending).