Civil Engineering Professional Engineer Practice Exam

What type of stress do structural members of arch bridges primarily experience?

1. Tension

2. Shear

3. Compression

4. Bending

The correct answer is: Compression

The structural members of arch bridges primarily experience compression due to the nature of the arch design. An arch bridge transfers loads from the bridge structure and any traffic above into compressive forces along the arch. When a load is applied, the shape of the arch allows it to efficiently redistribute the weight, creating a downward force that compresses the material of the arch itself. This compressive action is fundamental because it maintains the stability and integrity of the bridge. The curved shape of the arch prevents tension forces, which tend to pull apart the material, from dominating. While tension, shear, and bending stresses may exist in various parts of the bridge—especially at the supports or in other structural elements—the primary stress experienced in the arch members themselves is compression. This characteristic is a crucial factor in the overall design and engineering of arch bridges, enabling them to span greater distances while effectively supporting heavy loads.