Variable loads imposed on a structure by occupancy, furniture, equipment, and movable objects, as opposed to dead loads which are permanent structural elements.

Live load refers to variable loads imposed on a structure by occupancy, furniture, equipment, and movable objects, as opposed to dead loads which are permanent structural elements. These dynamic forces change over time and vary based on building use, occupancy patterns, and temporary conditions. Understanding live loads is essential for structural design, ensuring buildings can safely support all anticipated variable loads throughout their service life.

The primary purposes include accounting for variable occupancy loads in structural design, ensuring adequate structural capacity for intended building use, providing safety factors for unexpected load conditions, meeting building code requirements for different occupancy types, enabling proper sizing of structural members and foundations, supporting load path analysis and structural calculations, and ensuring long-term structural performance under varying conditions.

Types and categories involve occupancy loads, equipment loads, furniture loads, and environmental loads that vary over time and location.

Fun Fact: The first building codes specifying live loads were developed after the 1903 Iroquois Theatre fire in Chicago, which killed 602 people partly due to inadequate structural capacity for crowd loads! Modern building codes require office floors to support 50 psf, but actual office loads rarely exceed 15 psf. The live load for library stack areas can be 150 psf – equivalent to stacking books 7 feet high! Interestingly, dance floors require special consideration for rhythmic loading that can cause resonance and structural vibration!

• Average Load (Electrical)
• Dead Load
• Design Load