What is tension and torque have to do with bridges?

Tension and torque are two important concepts in engineering that play a crucial role in the design and analysis of bridges. Here's how tension and torque are related to bridges:

Tension:

Tension refers to the pulling force that acts on a structural member, such as a cable or a truss, when it is subjected to an external load. In the context of bridges, tension members are those that experience tensile forces, which means they are being stretched or pulled apart.

Suspension bridges, for example, rely heavily on tension members. The main cables of a suspension bridge are subjected to enormous tension forces due to the weight of the suspended deck and the traffic load it carries. These cables must be strong enough to withstand these tensile forces without breaking or deforming excessively.

Torque:

Torque, on the other hand, refers to the twisting force or moment that acts on an object or structural member, causing it to rotate or twist about an axis. In the context of bridges, torque is primarily associated with the structural components that support and transfer the loads to the foundation.

For instance, in arch bridges, the arch structure is subjected to torque due to the weight of the bridge deck and the traffic load. The arch acts like a curved beam that transfers the load to the supports by generating compression forces in the arch itself and tension forces in the tie rods or hangers. The shape and design of the arch are crucial to ensure that it can resist the applied torsional forces.

Similarly, in truss bridges, the diagonal members and web elements experience torque due to the external loads. These members are designed to transfer the torsional forces to the main structural elements, such as the top and bottom chords, and ultimately to the supports.

In summary, tension and torque are fundamental concepts in bridge engineering. Tension members withstand pulling forces, while torque refers to the twisting forces acting on structural components. Understanding and calculating these forces accurately is crucial for ensuring the stability, strength, and safety of bridges under various loading conditions.