Civil Engineering Professional Engineer Practice Exam

Arch bridges rely on the strength and rigidity of the arch itself for support. The primary structural feature of an arch bridge is its curved shape, which allows it to effectively distribute loads across its structure. When a load is applied to the bridge, the curved arch transfers the weight into horizontal thrust, which is then directed down into the supports at either end of the arch. This design efficiently manages both vertical and horizontal forces, making arch bridges particularly strong and stable.

While flexibility of materials, the weight of the bridge, and a solid foundation all play roles in the overall stability and performance of a bridge, they are not the primary structural features that provide the essential support in arch bridges. The unique geometry of the arch is what allows these bridges to span large distances without requiring extensive additional support, demonstrating the engineering principles behind this classic bridge design.