Live load is the weight of the moving or temporary elements that may be present on a structure, such as people, furniture, vehicles, snow, rain, wind, and any other dynamic or variable loads. Unlike dead load, live load is not constant and may vary in magnitude, location, and frequency. Live load is a crucial factor to be considered in the design of civil structures, as it affects the capacity of the structure to bear the load.
Different types of live loads with examples are:
- Occupancy load: This is the weight of the people who may be present on the structure, such as in buildings, stadiums, and other public spaces. The occupancy load is calculated based on the number of people and their average weight per unit area.
- Furniture load: This is the weight of the movable furniture and other equipment that may be present on the structure, such as in homes, offices, and other buildings. The furniture load is calculated based on the weight of the furniture and the number of items per unit area.
- Vehicle load: This is the weight of the vehicles that may be present on the structure, such as in parking garages, bridges, and roads. The vehicle load is calculated based on the weight of the vehicle and the number of vehicles per unit area.
- Snow load: This is the weight of the snow that may accumulate on a roof or other elevated surfaces, such as in colder climates. The snow load is calculated based on the weight of snow per unit area and the design snow load specified in the building codes.
- Wind load: This is the force exerted by the wind on the structure, such as on buildings, bridges, and towers. The wind load is calculated based on the wind speed, direction, and exposure of the structure.
To calculate the live load, various factors such as the type of structure, intended use, location, and occupancy must be considered. Building codes provide guidelines for calculating live load based on the type of structure and its intended use. The load calculations are typically based on a combination of the maximum expected load and a safety factor, to ensure that the structure can safely bear the load. Engineers may also conduct computer simulations and tests to verify the safety and performance of the structure under different live load scenarios.