Bridge Engineering MCQ with answer and solution

Concept

A bridge foundation carries loads from the superstructure, its own weight, and water effects such as buoyancy.

Step-by-step solution

1. List the forces that act on a bridge foundation. 2. Weight of superstructure (dead load and live load) goes to the foundation through the piers. 3. Self-weight of the foundation acts on the soil below. 4. Buoyancy acts when the foundation is in water or below the water table. 5. Seismic force is also a possible load, but the question seems to treat it as the odd one out.

Explanation

Weight of superstructure, self-weight of foundation and buoyancy are normal loads on a bridge foundation. Seismic force acts only in some cases and is the option most likely meant as 'not acting'. The question is poorly framed, so the key is uncertain.

Why the other options are wrong

Seismic force does act on foundations in seismic zones.

Shortcut

Look for the load that is not always present. Dead load, self-weight and buoyancy are common loads.

Common mistake

Forgetting that buoyancy reduces the effective weight on a submerged foundation.