Structural Dynamics-Types of load

 Dynamic loads are either predictable or random.

Another way to categorize the loads is based on its recurrence.

Loading that repeatedly exerted on structure with constant time interval is said to be periodic.

Some of them may be expressed in sine/cosine function, which make them simple harmonic motion.

Sources:

Earthquake data: http://www.vibrationdata.com/data.htm

Wind pressure data: https://www.ncdc.noaa.gov/cdo-web/datasets/LCD/stations/WBAN:41415/detail