Civil Engineering Professional Engineer Practice Exam

What does a unit of bending force primarily cause in materials?

1. Crushing

2. Twisting

3. Sagging

4. Splitting

The correct answer is: Sagging

A unit of bending force primarily causes sagging in materials due to the way that bending impacts the distribution of internal stresses. When a beam or structural element is subjected to bending, it induces tension and compression across different sections. The top fibers of the material experience compression, while the bottom fibers undergo tension. This differential stress leads to a curvature in the material, where the center of the beam typically experiences the greatest deflection or sagging. This bending phenomenon is central to the design and assessment of beams and other structural members, as understanding how materials respond to bending forces is crucial for predicting failure modes and ensuring stability under load. The sagging effect can lead to the development of local deformations and must be accounted for in the design phase to avoid structural failure.