Seismic Zones and Risk

What’s the Risk your property could experience an Earthquake?

All land has been assigned a hazard rating through the USGS, known as Seismic Design Categories from low to high risk. The map below shows areas throughout the United States.

Seismic codes or earthquake codes are building codes designed to protect property and life in buildings in case of earthquakes.

Seismic codes were created and developed as a response to major earthquakes which have caused devastation in highly populated regions. Often these are revised based on knowledge gained from recent earthquakes and research findings, and as such they are constantly evolving. There are many seismic codes used worldwide. Most codes at their root share common fundamental approaches regarding how to design buildings for earthquake effects, but will differ in their technical requirements and will have language addressing local geologic conditions, common construction types, historic issues, etc.

The following is from the EARTHQUAKE-RESISTANT DESIGN CONCEPTS publication from the National Earthquake Hazards Reduction Program

CHAPTER 5
DESIGN REQUIREMENTS - 5.1 Seismic Design Categories

The NEHRP Recommended Seismic Provisions recognizes that, independent of the quality of their design and construction, not all buildings pose the same seismic risk. Factors that affect a structure’s seismic risk include:
•The intensity of ground shaking and other earthquake effects the structure is likely to experience and
•The structure’s use including consideration of the number of people who would be affected by the structure’s failure and the need to use the structure for its intended purpose after an earthquake.

The Provisions uses the Seismic Design Category (SDC) concept to categorize structures according to the seismic risk they could pose. There are six SDCs ranging from A to F with structures posing minimal seismic risk assigned to SDC A and structures posing the highest seismic risk assigned to SDC F. As a structure’s potential seismic risk as represented by the Seismic Design Category increases, the Provisions requires progressively more rigorous seismic design and construction as a means of attempting to ensure that all buildings provide an acceptable risk to the public. Thus, as the SDC for a structure increases, so do the strength and detailing requirements and the cost of providing seismic resistance. Table 2 summarizes the potential seismic risk associated with buildings in the various Seismic

Design Categories and the primary protective measures required for structures in each of the categories. As noted in Table 2, structures are assigned to a Seismic Design Category based on the severity of ground shaking and other earthquake effects the structure may experience and the nature of the structure’s occupancy and use. The nature of the structure’s occupancy and use used in determining a Seismic Design Category is broken into four categories of occupancy as summarized in Table 3. Read more

RIDGURAK offers complete seismic services with most quotes. Rack structure quotes will match the appropreiate hazard area or seismic zone for the installation. Additionally, The Pelligrino Seismic Base Isolation System was designed to migitage the seismic energy of an earthquake on a rack structure. The Isolator shown here moves or travels under the rack's upright during a seismic event.