What is meant by 'live load' in a building context?

In the context of a building, 'live load' refers specifically to the weight of movable objects within the structure. This includes items such as furniture, equipment, and occupants that can change over time or be relocated. Understanding live loads is crucial in structural engineering and firefighting because they can significantly influence how a building behaves under various conditions, including during a fire emergency.

Designing a building involves calculating both live loads and dead loads (the weight of the building materials) to ensure it can safely support all expected loads throughout its lifespan. Live loads are typically variable and can fluctuate, unlike dead loads, which remain constant. Recognizing the distinction helps firefighters assess the structural integrity of a building during an emergency situation, especially when considering evacuation routes and potential hazards if the structure becomes compromised.