Civil Engineering Professional Engineer Practice Exam

What kind of force primarily acts on arch bridges?

1. Compression

2. Tension

3. Shear

4. Flexural

The correct answer is: Compression

Arch bridges are designed to efficiently transfer loads through the curved shape of the structure. The primary force that acts on arch bridges is compression. This means that as loads are applied to the bridge, such as the weight of vehicles or pedestrians, the arch shape allows these loads to be distributed along the curve of the arch and into the supports at each end. The compression forces effectively push inward along the arch, enabling the structure to remain stable and resist deformation. The inherent geometry of the arch also minimizes tension forces, which are not as prevalent in this type of design. This is advantageous because materials used in arch construction, such as stone or concrete, are typically stronger under compression than tension. In summary, the ability of arch bridges to maintain structural integrity under load is primarily attributed to the compression forces that are systematically managed by the arch’s design.