Live loads are dynamic in nature and may be generated from within or outside of the structure. Those from within are produced by the use and occupancy of the building and may be induced by human activity, vehicles in motion, or operational machinery and equipment.
Occupancy loads may also be classified as Superimposed Loads under the heading Gravity Loads.
Those from outside of the structure may be generated by vehicle traffic when in close proximity to a road or railway. Ice, snow and rain may also be classified as live loads.
Live loads fall into 4 major groups:
- Transient - which are usually associated with people or vehicles in motion such as would be encountered in public access areas or parking garages
- Periodic - which are associated with rhythmic human activity such as, dancing, marching in-step, or any other form of synchronized activity
- Harmonic - which are associated with rotating or vibrating equipment and machinery
- Impulsive - which are associated with sudden, non-rhythmic impacts as would typically be encountered in an industrial environment
The consequence of Live-Loads is Vibration, the frequency of which depends upon the nature of the Live-Load.