Earthquakes often occur due to slip between tectonic plates along a geological fault in the earth's crust. Earthquakes result
in various types of ground motion as seismic waves propagate through the earth. As these waves pass the location of a structure,
the associated ground motion
subjects the structure to lateral forces (primarily) and vertical forces (to a lesser degree).
Ground motion at the base of a structure results in dynamic loads (forces) distributed throughout the structure
based on the stiffnesses of structural elements (restoring forces) and the distribution of mass (inertial forces). The most accurate
methods of design for seismic loads involve comprehensive dynamic analyses of structures. However, simplified analytical
techniques (typically referred to as equivalent static force or equivalent lateral force procedures) are provided in model
building codes for the design of low-rise buildings subjected to seismic loads.
Since most wood structures are classified as low-rise buildings, this tutorial focuses on understanding and utilizing the
equivalent static (lateral) force procedures specified in the 2000 International Building Code (IBC) and the 1997 Uniform Building