Civil Engineering Professional Engineer Practice Exam

What type of forces do suspension bridges utilize to support their structure?

1. Compression forces

2. Moment forces

3. Tension forces

4. Bending forces

The correct answer is: Tension forces

Suspension bridges primarily utilize tension forces to support their structure. The design of a suspension bridge consists of large cables that are strung between tall towers, with the weight of the bridge deck hanging directly from these cables. When a load is applied to the bridge, such as from vehicles or pedestrians, the cables experience tension, effectively distributing the weight of the loads. This tension in the cables is essential because it helps to pull the deck upward and outward towards the towers, allowing the bridge to maintain structural integrity. The cables help to transfer this load to the towers and ultimately to the ground, balancing forces and helping to ensure stability. While compressive forces are essential elements in the towers that hold up the main cables, the main structural action of a suspension bridge comes from tension. Moment forces and bending forces do play a role in the bridge's overall behavior, especially in the deck and support elements, but they are not the primary forces utilized in the design of suspension bridges. Understanding the role of tension in these structures is crucial for civil engineering, as it influences both design and safety considerations.