What are the Essential Seismic Design Factors for Industrial Rack Systems?

Ensuring the safety of industrial steel storage racks is paramount, irrespective of where a facility is situated. However, the potential for earthquakes in a region, coupled with local building regulations, often necessitates more rigorous design standards for rack installations. To address this concern, the Rack Manufacturers Institute (RMI) has unveiled an enlightening educational video, running just under four minutes, delving into the seismic considerations crucial for rack designs.

Factors Influencing Rack Design

Geographical and site-specific elements significantly influence the design, engineering, fabrication, installation, and utilization of a rack system. Collaboration between the rack engineer and the facility owner is imperative, with the latter providing vital information such as:

• The current edition of the relevant building code enforced by the state, county, or municipality.

• Precise location details of the rack installation site.

• Pertinent information regarding the supporting concrete slab or floor.

• Soil characteristics beneath the building slab.
  

Identification of Seismic Design Categories

Seismic design categories classify facilities based on the expected severity of ground motion during an earthquake, ranging from A to F. Categories B and above mandate a seismic force review. Determining the anticipated earthquake intensity in a specific location involves referencing the Seismic Maps website (www.seismicmaps.org), where seismic parameters are provided based on the facility's address or coordinates.

Soil Classification

The type of soil at the installation site plays a crucial role in rack design considerations and is classified into several categories, including:

• Class A Soil: Hard rock

• Class B Soil: Rock

• Class C Soil: Very dense soil/soft rock

• Class D Soil: Stiff soil

• Class E Soil: Soft clay soil

Soil engineers determine the soil class, which, along with the seismic design category, informs the rack's design. In instances where soil classification is indeterminate, the design must adhere to Class D Soil requirements for safety.

Impact on Rack Design

Tailoring rack designs for maximum safety involves incorporating regional and site-specific information. For example, in high seismicity areas, increased horizontal clearance is necessary to mitigate collision risks between racks or other structures during seismic events. Moreover, enhancements such as reinforced connections, bracing, welding, frames, beams, base plates, and anchors are employed to prevent loads from dislodging and causing damage or injury.

Seismicity and Used Rack Components

The video underscores the bespoke nature of industrial steel storage rack structures, emphasizing that used rack components may not always be compatible due to differing seismic requirements across regions. Each rack is meticulously engineered to suit its specific location and application, ensuring optimal safety standards.