Civil Engineering Professional Engineer Practice Exam

How do arch bridges typically respond to the loads they carry?

1. They twist and flex

2. They bend significantly

3. They compress and distribute the load

4. They collapse easily

The correct answer is: They compress and distribute the load

Arch bridges are designed to efficiently handle loads through their specific geometric configuration. The arch shape inherently directs the weight of the load downwards and outwards along the curve of the arch. This design allows the forces to be transformed into compressive forces, which are effectively carried by the arch towards the supports at either end. By compressing and distributing the load, arch bridges utilize the materials' strength to maintain structural integrity and stability. As the load is applied, rather than bending or twisting, the arch's shape ensures that the stresses are evenly spread across the structure, minimizing the risk of failure. This characteristic makes arch bridges particularly effective for spanning large distances, as they can maintain their form and withstand significant weights without collapsing. In contrast, the other options do not accurately reflect the behavior of arch bridges under load. They do not experience significant bending or twisting, nor do they exhibit a tendency to collapse easily when designed and constructed properly. These properties underscore the efficiency and effectiveness of the arch form in bridge engineering.