Build Your Bridge to Success: Ace the 2025 Civil Engineering PE Exam!

Torsion refers to a twisting force that is applied to an object, typically along its longitudinal axis. In structural engineering, torsion occurs when a member, such as a shaft or beam, experiences a torque that leads to angular displacement. This twisting effect is crucial to consider when analyzing structures that may encounter torsional loading, such as in the case of bridges, tall buildings, or rotating machinery elements.

When a structural element is subjected to torsion, it can lead to shear stresses, which may result in failure modes that differ from those experienced under axial loads or bending moments. Understanding torsion helps engineers design elements that can resist these twisting forces, ensuring the structural integrity of the system.

The other options relate to different types of forces and structural effects: a compressive force refers to pushing forces acting along the length of a member, a bending moment describes the tendency of a force to cause rotation about an axis, and a static load pertains to forces applied to a structure that do not change with time. Each of these concepts plays a significant role in structural analysis but does not encompass the definition of torsion.