25 May 2005
IBC Section 1615 EARTHQUAKE LOADS SITE GROUND MOTION.
Seismic spectral response acceleration data is provided in appendices C and D for
specific locations. The short period spectral acceleration corresponding to a period of
0.2 seconds (SS) and the 1-second spectral period acceleration (S1) have been
identified for both the Maximum Considered Earthquake (MCE) and the 10/50
Earthquake, defined as an earthquake with a 10 percent probability of being exceeded
in 50 years.
The seismic design parameters in appendices C and D are typically provided
at the approximate geographical centroid of the installation / city. For larger installations
and where the potential seismic accelerations vary considerably over relative short
distances, it may not be adequate to use the acceleration values at the installation
centroid. At select locations the maximum and minimum value of SS and S1 within the
installation is listed. Use the maximum values unless site-specific location (latitude /
longitude) information is available and lesser values can be justified by the use of figure
1615 of the IBC or by approved computerized tools for determining seismic design
parameters. For additional guidance contact the authorizing design agency.
Within the United States. Seismic design data at DOD installations within
the United States, territories and possessions is identified in table C-2 to facilitate
consistent interpretation of the information provided in figure 1615 of the IBC. The data
was determined using the software, "Seismic Design Parameters" Version 3.10, and is
based upon geographical location data for each installation. This program or other
similar software may be used to determine seismic design data where site-specific
location information is available, with the approval of the authorizing design agency.
1-6.5.2 Outside of the United States. Seismic design data at specific locations
outside of the United States is identified in table D-2. Use the best available locality
information at locations where the earthquake accelerations are not provided. The
information shown is, with a few exceptions, not based upon detailed site-specific
assessments. If better information is available at a specific location it may be used with
the approval of the authorizing design agency.
Table E-1 in Appendix E provides best available seismic design data at
additional locations outside of the United States.
IBC Section 1805.2.1 Frost Protection. The minimum depth of footings
below the undisturbed ground surface must be 305 mm (12 inches). Protect foundation
walls, piers and other permanent supports of buildings and structures from frost as
described in the IBC as modified by UFC 1-200-01.
Depths to the frost line have been identified in table C-1 for locations within
the United States, territories and possessions, and in table D-1 for specific locations
outside of the United States. Use the best available locality information at locations
where frost depth values are not provided. For additional guidance contact the
authorizing design agency.