How do the concepts of "live load" and "dead load" differ in code calculations?

In structural engineering, "dead load" and "live load" are crucial concepts that help in calculating the weight and forces acting on a structure.

Dead load refers to the static forces acting on a structure, which typically include the weight of the building materials and any permanent fixtures. For example, the weight of beams, walls, roofs, and floor systems constitutes the dead load. This load is constant over time since these materials maintain their weight and position, and do not change during the lifetime of the structure.

On the other hand, live load refers to dynamic loads that can change over time and are not permanently applied to the structure. Live loads can include the weights of people, furniture, vehicles, and other movable items within a building. Unlike dead loads, live loads can vary significantly based on occupancy and use, meaning they must be calculated with consideration for different scenarios and maximum expected loads.

By identifying dead load as static and live load as variable, structural engineers can design safe and effective structures that can bear predictable and fluctuating forces. This distinction is essential in ensuring that buildings can withstand both the weight of permanent components and the changing loads from occupancy and use.