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Difficulty: MediumTypes of Stress and Strain

When a simply supported horizontal beam bends downward due to a heavy load applied at its center, the top surface of the beam experiences tensile stress, while the bottom surface experiences compressive stress.

Answer: Answer

Answer

False
When a simply supported horizontal beam bends downward, it forces the material on the top surface to push together and the material on the bottom surface to stretch apart. Therefore, the top experiences compressive stress and the bottom experiences tensile stress, making the statement false.

Step-by-Step Solution

1
Visualize the deformation of the beam under the central load.
The beam bows downward in the center, creating a U-like curvature.
Understanding the physical deformation is the first step to identifying the internal stresses.
2
Identify the effect on the top surface of the bent beam.
The top surface curves inward, causing its overall length to effectively shorten.
When a material's fibers are pushed together or shortened, it is under compressive stress.
3
Identify the effect on the bottom surface of the bent beam.
The bottom surface curves outward, causing its overall length to stretch.
When a material's fibers are pulled apart or elongated, it is under tensile stress.

Key Concept

Bending Stress in Structural Members
Estimated Time:30s
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Topics

Types of Stress and Strain

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