Civil Engineering Professional Engineer Practice Exam

Which of the following best describes bending force?

1. A force that compresses material

2. A force that stretches material

3. A combination of tension and compression acting on a structure

4. A force that creates shear

The correct answer is: A combination of tension and compression acting on a structure

Bending force is characterized by its ability to induce both tension and compression within a structure. When a beam or structural element is subjected to bending, one side of the element experiences compression while the opposite side experiences tension. This dual action is essential to the concept of bending; as the beam curves under the load, the material on the top side is pushed together (compressed), while the material on the bottom side is pulled apart (stretched or under tension). This phenomenon is commonly observed in beams and other structural members that carry loads perpendicular to their length. In the context of the other options, a force that compresses material refers mainly to compressive forces, which do not account for the tension aspect of bending. Similarly, a force that stretches material focuses only on tensile forces without considering the compressive aspect. Lastly, a force that creates shear pertains to a different mechanical action, where layers of material slide relative to each other, rather than the simultaneous tension and compression experienced in bending. Thus, understanding that bending involves both compression and tension allows for a more profound grasp of structural behavior under loads.