Civil Engineering Professional Engineer Practice Exam

Which force causes a structure to bend?

1. Compression

2. Bending force

3. Torsion

4. Shear force

The correct answer is: Bending force

The bending force is recognized as the primary cause of bending in structures. When a bending force is applied to a structural element, it creates a moment about a neutral axis, leading to tensile stress on one side and compressive stress on the other. This differential stress results in deformation, specifically bending. In structural engineering, understanding how bending forces come into play is essential for designing beams and other members to ensure they can withstand the loads applied without excessive deformation or failure. The bending force is key to analyzing beams in terms of their moment of inertia and the resulting stresses. Compression, torsion, and shear force represent different types of loading conditions. Compression involves pushing forces that tend to shorten an object, torsion relates to twisting forces that can cause a structure to rotate, and shear forces arise from loads that cause different parts of a material to slide past one another. While these forces can be present in a structure under load, it is specifically the bending force that is responsible for causing the bending phenomenon itself.