1mW SD002

1mW Structural Design 002

Permanent and Variable Actions

Actions acting on structure are categorized based on the variation of their magnitude with respect to time.

For those with very small variation, they are classified as permanent actions. These actions are equivalent to dead load. Some examples of permanent actions are the self-weight of structure and non-structural component, fixed equipment and road surface.

Actions with significant variation of magnitude over time may be categorized as variable actions. These actions are equivalent to live load, where imposed load, wind actions and snow loads are included.

For action with very large variation in short period of time, it should be classified as accidental load. Accidental loads can also be described as impact load, which include either explosion or impact from vehicles.