Civil Engineering Professional Engineer Practice Exam

What is a crucial feature of arch bridges regarding load distribution?

1. Load is concentrated at mid-span

2. They transfer load to the ends only

3. They can distribute load to abutments

4. They rely solely on tension

The correct answer is: They can distribute load to abutments

Arch bridges are designed with a unique geometric shape that allows them to effectively distribute loads. A crucial feature of arch bridges is their ability to distribute the load to the abutments. When a load is applied to the arch, it is transmitted through the arch’s curvature and down to the supports at either end. This means that the gravitational forces exerted on the bridge are not just concentrated at a single point but are instead spread outward along the arch’s curve, allowing the loads to be efficiently transferred to the supporting structures, or abutments. This load distribution mechanism is essential because it helps to minimize bending stresses in the bridge materials, making them particularly effective for spanning longer distances with minimal material usage. The design relies on the principles of compression, with the arch pushing down and outward, ensuring that the entire structure can work together to support the loads without excessive strain on any one part of the bridge. Understanding this feature is critical for civil engineers, as it underlines the importance of material selection and structural design in ensuring the safety and longevity of arch bridges.