Civil Engineering Professional Engineer Practice Exam

What is the main section of a suspension bridge compared to?

1. A horizontal beam

2. A traditional arch bridge

3. An upside-down arch bridge

4. A cantilever structure

The correct answer is: An upside-down arch bridge

In a suspension bridge, the main section, which consists of cables supporting the deck, can be likened to an upside-down arch. This comparison highlights the way the forces are distributed throughout the structure. In a traditional arch bridge, the arch shape allows for compression to effectively transfer loads down to the supports. Conversely, in a suspension bridge, the cables are subjected to tension as they hold up the weight of the bridge deck. When viewed in profile, the arrangement of cables creates a curve that resembles the inverted shape of an arch. The tension in the cables is a critical factor that allows the bridge to span large distances, distributing loads to the towers and securing stability. This concept helps clarify the unique structural mechanics of suspension bridges compared to other bridge designs. Understanding this comparison is key for civil engineering concepts, as it emphasizes how different structures utilize geometric shapes to manage forces effectively.