Have you ever wondered, “Do I really need a special equipment rack in a seismically active area?” The short answer is “Yes.” Using a rack or cabinet designed for seismic applications may be more costly, but will give you the highest load-bearing capacity in your designated floor space.
The Benefits of Seismic Racks
One of the main purposes of an equipment rack is to store a large amount of equipment while using a relatively small amount of floor space. Essentially, it lets you stack equipment vertically. The EIA-310 standard is universally adopted, so you can easily designate a number of vertical rack-mount spaces (U) for equipment. What changes from rack to rack and by manufacturer is the rated load capacity, or the amount of weight each rack can safely hold. To allow for future expansion, seek a solution with the highest load per rack, even if you do not immediately need it. This maximizes load per U, allowing for the best value from the designated floor space and rack.
Typically, manufacturers only publish the static equipment load of their racks (or cabinets) in product specifications. The range is between 1,500 to 3,500 pounds per rack, depending on the rack type. However, it is important to remember that the static equipment load provides the value for “non-seismic” equipment load. This is how much the rack can safely hold when still and does not consider the effects of vibration on the rack. Seismic equipment load must be calculated separately based on code requirements.
What Makes Seismic Racks Different?
The seismic equipment load of a rack will be less than its static equipment load unless the rack is specifically designed for seismic applications. Racks designed for seismic applications have heavily-braced frames that resist side-to-side, front-back and up-down movement. Most manufacturers load-test these racks on shaker test tables that simulate seismic events to demonstrate rack performance, and verify their load claim. A motion limit must be maintained throughout the test and the rack has to survive the test with no structural damage.
The International Code Council (ICC), which publishes the International Building Code (IBC), the model code in the United States, publishes seismic test procedure ICC ES AC-156. Several standard shaker tests are available. Traditionally, rack manufacturers used the Telcordia Technologies GR-63-CORE, Section 4.4 test for rack and rack-mount equipment.
Choosing the Right Rack
Which rack or cabinet should you use? The building code requires that a licensed structural engineer design the components, supports and attachments for nonstructural building components such as equipment racks. That means an engineer defines the exact installation hardware, placement and materials that attach the rack to the floor and, if necessary, how it will be braced overhead. The design includes a calculation to determine the seismic load. With this design, you can use any rack in a seismic area. However, the penalty may be a greatly reduced equipment load if you do not select a rack specifically designed for seismic applications.
Racks designed for seismic applications are more expensive than non-seismic racks, but generally have higher load ratings and can be filled with equipment. Non-seismic racks may require multiple racks to support the same amount of equipment.
Special Considerations for California
For design guidance, consider the California Office of Statewide Health Planning and Development’s (OSHPD) “Preapproval of Manufacture’s Certification” (OPM) program. In the state of California, OSHPD has permitting and inspection authority over all heathcare facilities. California adopts the model building code with additions that increase seismic requirements.
To speed the design process for common building components, OSHPD created the voluntary OPM program. OPM allows manufacturers to engage an engineering firm to develop a standard anchorage recommendation for their product. Once reviewed and approved by OSHPD, the recommendation is posted to the OSHPD website and can be referenced for use in any OSHPD-permitted project. It speeds the permitting process and plan review while providing general guidance on installation practice for common building components.
The Best Option for Your Facility
OPM defines the product and installation practices that meet the most stringent requirements of the model code. If you are in the market for a seismic rack for your facility, use OSHPD's OPM to short list a few of your favorite racks. Then, compare the details to find the highest seismic load. For permitting approvals outside of California, you will need a local engineer to make the recommendation, but he or she should be able to adopt the OPM.