Which type of load changes in magnitude and location over time due to occupancy or use?

The correct answer is dynamic load. This type of load is characterized by changes in magnitude and location over time, influenced by factors such as occupancy, use, or external forces like wind or earthquakes. Dynamic loads are crucial in civil engineering as they represent situations that structures must be designed to accommodate, such as moving vehicles on a bridge or people in a building.

Dynamic loads are particularly important because they can introduce varying forces that may affect the structure's performance. Understanding these loads helps engineers anticipate how structures will behave under real-life conditions, which often involve fluctuating and shifting loads.

In contrast, dead loads are constant, static loads that do not change over time, typically representing the weight of the structure itself and any permanent fixtures. Static loads, while they can include both dead and live loads, refer generally to loads that do not change over time but do not necessarily capture the transient nature of loads experienced during occupancy. Impact loads are a specific type of dynamic load that occurs suddenly and is typically associated with a short duration, such as a collision.

Recognizing the distinction between these different load types is essential for proper structural design and analysis.