Correct Answer - Option 2 : Where bending stress is uniform at maximum bending moment of the section
Explanation
We know,
The bending equation states that:
\(\frac{\sigma }{y} = \frac{M}{I} = \frac{E}{R}\)
Various terms in the above bending equation are:
σ = Bending stress, y = Distance from the neutral axis
M = Bending moment, I = Area moment of inertia
E = Modulus of elasticity, R = Radius of curvature
A beam of Uniform Strength
- In general, beams have uniform cross-sections throughout their length. When they are loaded, there is a variation in bending moment from section to section along the length. The stress in extreme outer fiber (top and bottom) also varies from section to section along their length.
- The extreme fibers can be loaded to the maximum capacity of permissible stress, but they are loaded to less capacity. Hence, in beams of the uniform cross-section, there is a considerable waste of materials.
- When a beam is suitably designed such that the extreme fibers are loaded to the maximum permissible stress by varying the cross-section it will be known as a beam of uniform strength.
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The beam is said to be in uniform strength if the maximum bending stress is constant across the varying section along its length.
To make a Beam of uniform strength the section of the beam may be varied by
- Varying the depth by keeping the width constant throughout the length
- Varying the width by keeping the depth constant throughout the length
- By varying both width and depth suitably
