A previous post explored the changes in ANSI MH16.1-2023: Design, Testing, and Utilization of Industrial Steel Storage Racks specific to a recently updated methodology for performing seismic and stability calculations. These changes were part of rack design standard updates routinely made by the members of the Rack Manufacturers Institute (RMI). Because the International Code Council’s International Building Code (IBC) references ANSI MH16.1-2023 as governing the safe design and installation of steel storage racks, the latest seismic and stability calculations are part of the newest IBC, published in 2024.

Also in the previous post, Christopher Aprile, Senior Structural Engineer with RMI member Steel King Industries, explained how the new analysis method differs from the previous one. He also urged rack manufacturers to adopt the new methodology sooner than later.

Said Aprile, “Ideally rack engineers need to start to comply with the new methodology for seismic and stability calculations soon if they have not already. This new method may, in certain project areas with a higher likelihood of seismic events, result in a more robust storage rack design. That, in turn, could increase the cost of the rack system as a whole.”

Rack Types Potentially Affected by Newer Seismic Calculations

It is, Aprile said, important to note that the new seismic calculations only apply to the types of racks and related structures covered by ANSI MH16.1-2023. Those include industrial steel storage racks constructed of cold-formed or hot-rolled structural steel members, including:

• Movable shelf racks
• Rack supported systems
• Racks associated with automated storage and retrieval systems (AS/RS)
• Pallet flow rack
• Case flow rack
• Pick modules
• Rack supported platforms

“Also, existing systems whose design was based on seismic calculations modeled in older versions of ANSI MHI16.1 do not require modification to the new standard. They can continue to be in service,” stressed Aprile. “Their engineering reflects an earlier approved design standard, so they are grandfathered in. Any new rack system additions, repairs, or modifications, however, may be subject to the new seismic calculations per the latest ANSI MH16.1 standard.”

R-Mark® Certification Indicates Suppliers’ Compliance with RMI Standards

Aprile also recommended that rack purchasers determine which version of the ANSI MH16.1 standard a rack manufacturer uses as part of their supplier vetting process. RMI’s R-Mark certification program makes it easy to find out by visiting its list of certified companies.

To receive R-Mark certification, a rack manufacturer must submit a comprehensive application to RMI. “There is an independent third-party engineering review performed by a professional engineer with extensive rack industry experience. The application details how the manufacturer meets applicable RMI standards in its design, engineering, and manufacturing processes,” explained Aprile.

“Several storage rack companies have obtained — or are in the application process for — R-Mark Certification to the ANSI MH16.1-2023 standard, which had minimal revisions compared to the 2021 version,” he continued. “Any company certified to ANSI MH16.1-2021 before the 2023 version being issued should comply with the ANSI MH16.1-2023.”

Aprile noted that the application includes engineering design structural calculations (low and high seismic) and certified lab-tested connection stiffnesses. These submissions are part of a test data package that includes manufacturing documents, sample lab test reports, and structural analysis calculations.

“The applicant must submit separate test data packages for each type of product they offer relative to the specific standard. That includes cold-formed steel rack or hot-rolled structural steel rack,” he added. “The R-Mark evaluation is very comprehensive and thorough.”

Installing Rack in an a High-Seismicity Region?

RMI has rack design resources available, including frequently asked questions and answers specific to seismic considerations. These cover ANSI MHI16.1-2023: Design, Testing, and Utilization of Industrial Storage Racks, rack design reviews, seismic design categories, seismic factors and site coefficients. They also address soil classifications, seismic separation, redundancy, and the newest seismic maps. Further, RMI also a video, Seismic Considerations for Rack Designs, on its website.