Datacenter
Seismic certification for prefab data center modules
Seismic certification for prefab data center modules combines structural design, equipment qualification and site connection approval. Match all three to the delivered configuration.
Direct answer
Seismic certification for prefab data center modules requires a coordinated package: structural design for the module and foundation, seismic qualification of equipment where required, and approved supports, anchors and utility connections for the installation site. An AC156 shake-table report covers its identified equipment and mounting conditions; it does not by itself approve the entire module. The adopted code, project engineer and authority having jurisdiction determine the required evidence.
On this page
What does seismic certification for a prefab module cover?Which codes and editions apply in November 2026?Does every data center module require special seismic certification?What must an AC156 test report show?Can you use an OSP listing or an older certificate?What changes when certified equipment sits inside a module?How do you compare certification capacity with project demand?How does a weight change affect the connection review?What belongs in the seismic submittal?What do you check at factory release and delivery?What must crews verify before closing the module?Which changes need another engineering review?How should you scope and price certification work?What should the owner receive at turnover?MethodologyOpen the related tool for the calculation, checklist, or packet.
FieldOS by AnvilfieldOffline-first FieldOS for job photos, proof packets, property memory, calculations, teams, billing, and owner-ready reports.Key takeaways
- Define whether the module is a building, a nonbuilding structure or equipment before selecting its seismic design path.
- Match the exact equipment, operating weight, mounting arrangement and qualification envelope to the approved project demand.
- Keep equipment certification, supporting-frame design and foundation anchorage as connected but separately documented approvals.
- Treat substitutions, changed supports and relocation as review triggers before releasing the affected work.
What does seismic certification for a prefab module cover?
A prefab module needs evidence for the enclosure and supporting frame, the equipment inside, and the connections carrying loads into the site. Start the review by drawing those boundaries on one sheet. A cooling skid, a transportable electrical room and a stackable IT enclosure can have different structural classifications even when the purchase order calls all three modules.
Ask the structural engineer and authority having jurisdiction, or AHJ, to establish the classification and approval route. Building design, nonbuilding structure design and nonstructural component qualification answer different questions. The certification package must follow the selected route. Neither a shipping-container identification plate nor an equipment test certificate settles that classification.
Separate the performance goals too. Keeping the module standing, retaining equipment, demonstrating equipment function after specified shaking and maintaining the complete data center service are different outcomes. Write the owner's required recovery and operating functions into the procurement specification so the supplier knows what evidence to provide.
For example, a certified switchboard can sit inside a module whose floor connection has never been checked for that switchboard's reactions. Conversely, an adequately designed frame can contain controls outside the tested product configuration. Keep a responsibility matrix with a named designer and document for each boundary; otherwise the missing connection can remain unassigned.
| Approval boundary | Evidence to request | What remains to be checked |
|---|---|---|
| Module enclosure and structural frame | Project structural calculations, drawings and design criteria | Site hazard, support conditions, openings and module-to-module connections |
| Equipment inside the module | Applicable certificate, test report and covered product schedule | Exact model, options, weight, mounting and required function |
| Equipment supports and site anchorage | Approved connection drawings, reactions and anchor calculations | Actual frame, foundation, anchor installation and inspection |
| Power, cooling and control interfaces | Movement details and project commissioning requirements | Installed clearances, flexible connections and system operation |
Which codes and editions apply in November 2026?
Use the permit's adopted editions, amendments and approved design criteria. This guide uses the 2024 International Building Code, or IBC, and ASCE/SEI 7-22 as its current structural reference. ASCE 7 is the loading standard; its Chapter 13 addresses nonstructural components. Do not apply Chapter 13 alone to a module that the project classifies as a building or nonbuilding structure.
ASCE 7-22 places special seismic certification in Section 13.2.3. Older material commonly points to Section 13.2.2. HCAI's October 2025 revision of Policy Intent Notice 55 uses the newer reference. Its April 2025 technical presentation also explains changes to the horizontal component force equation. Copying an older certificate's equation into a current submittal without reconciling editions can miss changed demand.
ICC-ES identifies its current criterion as AC156 (24), 2nd Edition, published April 2025. Record the actual criterion edition used by the laboratory, the certificate's code basis and the project's acceptance decision. A catalog saying AC156 without an edition is incomplete evidence.
For electrical coordination, use NFPA 70, the National Electrical Code, 2026 where adopted; otherwise this guide's electrical reference is NEC 2023. Confirm the local adoption before citing Article 646 for modular data centers. California provides a concrete example: its 2025 California Electrical Code adopted NEC 2023 with amendments, effective January 1, 2026. NEC publication year does not establish local adoption.
UL Solutions identifies UL 2755:2025 as replacing its 2018 outline and addressing integrated modules, including structural considerations. Request the actual evaluation scope and installation conditions. A UL listing, equipment seismic certificate and site structural approval each contribute evidence; no product mark alone establishes every project approval.
Does every data center module require special seismic certification?
No single rule makes every data center or every item inside it an essential facility requiring the same certification. The design professional establishes the building risk category, seismic design category and component importance factors from the adopted code and actual function. An owner can specify additional performance, but calling a facility mission critical does not assign its code category.
The component importance factor, Ip, is one input to the review. Determine which equipment falls within the adopted special-certification provisions and which exemptions apply. Do not turn Ip = 1.5 into a blanket instruction to shake-test every rack, pipe and bracket. Likewise, an exemption from special certification does not establish an exemption from applicable restraint, support or anchorage requirements.
Active equipment raises a specific question: what demonstrates that its operating function survives the required shaking? A strength calculation for the cabinet shell does not establish that a controller, breaker mechanism or pump assembly functions afterward. The accepted qualification method must address the required performance.
California healthcare rules need particular care. HCAI's current PIN 55 explains the shake-table basis of its preapproval program and the stricter treatment of active or energized equipment under the applicable hospital provisions. Use those rules where that jurisdiction and facility scope apply. Do not export hospital-specific requirements to every commercial data center.
What must an AC156 test report show?
Read the certificate with its supporting test report and installation drawings. Identify the unit under test, or UUT, including the enclosure, internal equipment, accessories, operating contents, weight and mounting arrangement. A certificate covering a product family needs a documented basis for including the purchased member of that family.
The required response spectrum, or RRS, describes the required shaking over frequency. The test response spectrum, or TRS, records what the laboratory produced. Have the responsible reviewer confirm coverage in the required horizontal and vertical directions, along with the report's acceptance criteria and functional checks. A single advertised g-value hides information about frequency, direction and support conditions.
The test setup matters because a rigid laboratory fixture and a flexible module floor can transmit different motion. HCAI's PIN 55 addresses mounting configurations and supporting stiffness explicitly. Ask the supplier to explain how the tested setup represents the installed supports or how the qualification accounts for their response.
Read the test outcome, not just the cover sheet. Identify any reinforcement, replacement parts or other changes incorporated to resolve test findings, and trace the required final configuration into production drawings. Ask what functionality was checked before and after the test and what operating state applied during shaking. A reported functional check is evidence for that defined scope, not an unlimited claim of uninterrupted data center operation.
Can you use an OSP listing or an older certificate?
An OSHPD Special Seismic Certification Preapproval, or OSP, is HCAI's voluntary equipment preapproval route for California healthcare construction. It can provide useful qualification evidence elsewhere when accepted by the project reviewer and AHJ. It is neither a nationwide building permit nor automatic approval of the enclosing prefab module.
Use the complete listing. Schneider Electric's agency-hosted OSP-0022, for example, identifies QED-2 and Speed D switchboards, rigid floor mounting and a covered component matrix. Its published certificate carries a CBC 2022 basis. That makes it a useful example of configuration-specific evidence, not proof that a new project under a different code has already been approved.
For an older report, reconcile the applicable code, qualification spectra, mounting, covered options and certificate status. HCAI's 2025 transition guidance explains comparison of existing tested spectral parameters with the new project demand. It specifically distinguishes older analytical Fp/Wp values from the tested spectral acceleration parameters. Comparing only the front-page force ratio can answer the wrong question.
Check the issuing agency's record and the project acceptance conditions. Expiration, renewal and grandfathering depend on the program and project circumstances. A supplier's statement that a product was certified years ago needs the actual report and a written disposition for this installation. Preserve that disposition with the submittal rather than relying on an email saying the model has not changed.
What changes when certified equipment sits inside a module?
Follow the force from each cabinet or skid through its feet, mounting rails, floor beams, module frame, site connections and foundation. Each link needs a compatible design basis. A certificate for equipment attached to a rigid floor does not establish that thin decking, a field-added channel or a raised curb behaves like the tested support.
Request equipment reactions at the actual connection locations and module reactions at the actual site support points. Coordinate operating weights, centers of gravity, liquid contents, future loading and the proposed restraint details. Record whether reactions belong to a strength or allowable-stress design basis so reviewers do not compare unlike quantities.
Stacking modules, lifting them onto pedestals or placing equipment on an upper module floor changes the supporting arrangement. Have the engineer evaluate the applicable structural response and component demand. Equipment inside a module resting on grade is not automatically equivalent to equipment anchored directly to a rigid foundation at grade.
Connections crossing the module boundary deserve their own drawing. Cooling pipes, bus connections, conduit, cable trays and control wiring must accommodate the specified relative movement without creating an unintended rigid tie. Show clearances and the approved connection arrangement at each crossing. The goal is an installation that follows the reviewed movement detail, not simply a flexible-looking hose in a delivery photo.
How do you compare certification capacity with project demand?
Anvilfield analysis of the equipment-screening case gives demand-to-qualified-capacity ratios of 0.80, 0.80, 1.14 and 0.91. The flexible-region vertical demand exceeds capacity, so this case does not pass the stated qualification comparison.
The table reports comparable spectral parameters in multiples of gravitational acceleration, g. H identifies horizontal and V vertical. Check the full spectra, frequency ranges, directions and report conditions for the actual project.
Qualification spectra establish equipment-test coverage; they are not interchangeable with the analytical force coefficient for designing supports or anchors. HCAI's transition guidance distinguishes these quantities.
Record the equipment model, options and mounting arrangement with the numerical comparison. A changed support or unreviewed isolator remains an approval issue even when selected demand ratios are below the qualification values.
| Band | Demand | Limit | Ratio |
|---|---|---|---|
| H flexible | 1.20 g | 1.50 g | 0.80 |
| H rigid | 0.48 g | 0.60 g | 0.80 |
| V flexible | 0.80 g | 0.70 g | 1.14 |
| V rigid | 0.32 g | 0.35 g | 0.91 |
How does a weight change affect the connection review?
Anvilfield analysis gives 10.8 kip horizontal force, 43.2 kip-ft moment and a 5.4 kip force-couple contribution for the 18,000 lb equipment case.
With operating weight increased to 21,000 lb and the same coefficient and geometry, the results become 12.6 kip, 50.4 kip-ft and 6.3 kip. Each increases by 16.7 percent. Send the changed equipment weight and arrangement for connection and qualification review.
The force couple describes the moment across the two support lines. Anchor design still needs gravity and vertical seismic effects, load combinations, stiffness, eccentricity and connection behavior. A mass change also requires review of the dynamic response and applicable coefficient.
What belongs in the seismic submittal?
Build a package that lets the reviewer trace one delivered module from the permit criteria to the smallest approval boundary that matters. Start with a module identifier, drawing revision and equipment schedule. Cross-reference certificates to individual equipment tags, not just to the vendor's name.
Use a review status beside every document: submitted, accepted, revise or awaiting information. Keep unresolved issues specific. A useful comment says that cabinet P-02 has a different mounting rail from the tested configuration and identifies who must resolve it. An unhelpful comment says seismic certification pending with no boundary or owner.
The table is a recommended coordination structure, not a universal list of permit deliverables. The project specifications and AHJ determine the required signatures, seals, delegated-design process and inspection submissions. Agree on those requirements before the factory release date so the package can be reviewed while the work is still accessible.
| Document | Minimum useful identifiers | Reviewer question |
|---|---|---|
| Design criteria | Adopted editions, site, risk category, seismic design category and assigned component factors | Is this the permitted project basis? |
| Module structural package | Frame revision, equipment layout, operating loads and support reactions | Is the complete structural load path addressed? |
| Equipment qualification | Certificate, test report, UUTs, model matrix, options and spectra | Does the purchased configuration satisfy this demand? |
| Support and anchorage drawings | Equipment tags, base details, anchors, substrate and connection reactions | Do installation and qualification conditions agree? |
| Interface drawings | Movement allowances and power, cooling and control crossings | Can adjacent systems move as designed? |
| Inspection and release record | Hold points, required witnesses, deviations and approval references | What must close before shipment and concealment? |
What do you check at factory release and delivery?
Recommend a factory hold point after the final equipment arrangement is installed and before inaccessible work is closed. Compare nameplates, equipment tags, restraint hardware and mounting details with the accepted package. Photograph connection locations while a reviewer can still see the attachment and supporting member together.
Keep factory acceptance testing separate from seismic qualification. A factory acceptance test, or FAT, exercises the functions defined in the commissioning plan. It does not become an earthquake test because the equipment runs successfully. The FAT can confirm the delivered configuration and record functions for later comparison, while the qualification report establishes its separate seismic evidence.
At delivery, identify shipping braces and temporary restraints against the manufacturer's transport and installation instructions. Some transport hardware must be removed; permanent restraints must remain. Resolve unlabeled hardware with the supplier before the crew changes it. Record visible damage, displaced components and any repairs against the specific module and equipment tags.
Treat unexplained shipping changes as open items. If a mounting bracket was replaced to fit the trailer or a cabinet arrived with a different accessory, preserve the discrepancy and obtain a disposition. A clean bill of lading is not the record establishing that the delivered configuration still matches the accepted certification package.
What must crews verify before closing the module?
Walk the accessible load path with the approved drawings and the assigned inspector. The field crew verifies the installed condition; the engineer resolves design changes. Schedule required special inspection before anchors, welds or supporting members become inaccessible, and use the project's inspection plan to determine the required observation and records.
Use this checklist as a coordination aid. Record measured or observed conditions and the document used for comparison. An anchor photo can show location and visible hardware, but it cannot establish hidden embedment or substitute for required installation records. Keep acceptance tied to the responsible review.
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Which changes need another engineering review?
Flag changes to equipment model, internal components, operating weight, center of gravity, support stiffness, attachment location, mounting orientation and installation elevation. Also flag a new opening or cut in the module frame near the load path. These changes can affect different parts of the approval package, so identify the changed boundary rather than declaring the whole system automatically recertified or invalid.
HCAI's current PIN 55 distinguishes changes within approved limits from material changes affecting structural integrity or functionality. Apply the governing program's actual rules and obtain the supplier's and engineer's documented evaluation. Some changes can be resolved through existing qualification and calculations; others require additional testing or a different product.
A relocated module deserves a fresh site comparison. Retaining the same steel box does not retain the previous soil conditions, seismic hazard, foundation details or utility interfaces. Keep the original documents as evidence, then document which design inputs remain applicable and which must be replaced for the new installation.
How should you scope and price certification work?
Price the review boundaries explicitly: module structural design, equipment qualification, support and anchorage design, factory verification, site inspection and change review. Ask whether the supplier's price includes a project-specific certificate, access to supporting reports, engineering responses and revisions after the final equipment schedule. A quote for seismic anchorage alone can leave equipment qualification unpriced.
Build the estimate from actual effort and supplier quotations. Separate an existing covered product from a custom configuration needing an engineering assessment or testing. Identify the number of module variants, installation sites and review cycles. Do not invent a universal certification fee or lead time; laboratory availability, redesign and approval scope have to come from the parties doing the work.
For electrical crews pursuing public module installations, PorchRocket's Bid Control tracks Texas city, county and school electrical bids. Read the issuing agency's package to establish whether the opportunity includes modules, foundations, equipment qualification or only field connections. A public electrical bid is a starting point for scope review, not evidence that a particular owner needs seismic recertification.
Give exclusions an owner and a handoff date. If the integrator supplies equipment certificates but the site contractor supplies anchorage, identify who reconciles the two before fabrication. Carry unresolved interface work as an open estimating input that must close, rather than burying it in a general allowance.
What should the owner receive at turnover?
Deliver the approved design basis, final module and equipment schedule, applicable certificates, report references, connection drawings, inspection results and resolved deviations as one indexed record. Link every equipment tag to its qualification and installed location. Include the supplier contact and the conditions governing replacement parts or future changes.
Keep seismic evidence and commissioning evidence alongside each other with distinct acceptance statements. Site acceptance testing and the integrated systems test show the installed power and cooling functions under the agreed scenarios. They do not reproduce the qualification earthquake or expand the certificate's model coverage.
Use the related modular deployment guide for the overall delivery sequence, the seismic anchoring and anchor-bolt guides for connection coordination, and the structural rack guide for loading discussions. The commissioning, liquid-cooling and grounding guides cover adjacent acceptance work. This record closes the certification boundaries between those disciplines; it does not replace their project deliverables.
Methodology
Anvilfield research uses the adopted-code and qualification documents linked below to define the review boundaries. HCAI guidance distinguishes equipment spectra from support-force calculations. The numerical cases use stated screening inputs; they do not assign a site hazard or a project design coefficient.
For the spectrum case, demand/capacity pairs are H flexible 1.20/1.50, H rigid 0.48/0.60, V flexible 0.80/0.70 and V rigid 0.32/0.35, all in g. Ratios are 0.80, 0.80, 1.142857 and 0.914286, rounded to two decimals. The case holds model, operating configuration and mounting constant, with both horizontal directions covered by the input envelope.
The equipment case uses operating weights of 18,000 and 21,000 lb, an input horizontal coefficient Fp/Wp of 0.60, center-of-gravity height 4 ft and support spacing 8 ft. Force is coefficient x weight; moment is force x height; the force-couple contribution is moment / spacing. Dividing the weight increase by 18,000 gives 16.6667 percent, reported as 16.7 percent. Full support and anchor design adds the applicable load combinations and structural response.
FAQ
Does an AC156 certificate approve the entire prefab data center module?
Only the identified scope and configurations are covered. An equipment report does not automatically approve the enclosing structure, supporting floor, foundation or utility connections. Check the report boundary against the project's module classification and structural documents.
Is UL 2755 certification the same as seismic certification?
No. UL 2755:2025 addresses integrated modular data center safety and includes structural considerations. Review the actual evaluation scope. Equipment seismic qualification and project-specific structural and anchorage approval must still be established where required.
Does every data center require Ip = 1.5 equipment?
No. The design professional assigns component importance factors under the adopted code and actual component function. A commercial uptime target does not automatically assign the building's risk category or require special certification of every component.
Can structural calculations replace a shake-table test?
Only where the applicable qualification provisions permit that method. Calculations can establish structural resistance without proving active equipment functionality. HCAI's OSP program uses approved shake-table evidence; its hospital rules for active or energized equipment must be checked separately.
Can an older certificate support an ASCE 7-22 project?
Potentially, with a documented comparison accepted by the responsible reviewers. Reconcile the code basis, tested spectra, configuration and mounting against the new project. Do not treat the older certificate's analytical Fp/Wp ratio as its tested spectral acceleration envelope.
Does installing stronger anchors make an uncertified configuration acceptable?
Stronger anchors address only part of the load path. They do not establish the cabinet's internal functionality or the suitability of changed supports. Obtain the equipment qualification and connection reviews required for the actual configuration.
Is a factory acceptance test sufficient seismic evidence?
No. A FAT verifies the commissioning functions in its test plan. Seismic qualification establishes performance under specified shaking. Keep both records and reconcile their equipment configurations, but do not substitute one test for the other.
Which NEC edition does this guide use?
NEC 2026 where adopted, otherwise NEC 2023 for the electrical coordination discussed here, subject to the jurisdiction's actual adoption. California's 2025 Electrical Code uses NEC 2023 with amendments and became effective January 1, 2026. Structural seismic criteria come from the adopted building code and loading standard.
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Codes cited in this guide
This guide is written and reviewed against the published standards below. Always confirm the current adopted edition with the authority having jurisdiction.
Sources checked
- ASCE: ASCE/SEI 7-22 Opened with curl for the November 5, 2026 review. Publisher overview of the loading standard and hazard tool; use the adopted standard and project criteria for design.
- ICC: 2024 IBC significant structural changes Opened with curl. Supports the 2024 IBC and ASCE 7-22 context, risk-category discussion and need to distinguish structural design from component qualification.
- ICC-ES: AC156 (24), 2nd Edition Opened with curl. Official criterion identification and scope. The landing page identifies the current edition; it is not the full paid criterion.
- ICC-ES: April 2025 acceptance-criteria edition notice Opened with curl. Confirms the AC156 (24), 2nd Edition designation and April 2025 publication date used in the edition discussion.
- HCAI: PIN 55, revised October 23, 2025 Opened with curl through HCAI's official document link. Current OSP scope, ASCE 7-22 Section 13.2.3 reference, mounting and support conditions, project implementation and configuration-change rules. Hospital-specific provisions are identified as such in the guide.
- HCAI: 2025 CBC changes to preapprovals and ASCE 7-22 Opened with curl. Explains changed component-force inputs and comparison of existing qualification spectra with project demand. The numerical cases use the screening inputs recorded in Methodology.
- Schneider Electric: OSP-0022 switchboard certification, hosted by HCAI Opened with curl through HCAI's official OSP-0022 link. Manufacturer-specific example of model coverage, rigid mounting and configuration limits. Its CBC 2022 basis is explicitly identified; it is not presented as automatic approval under a newer code.
- UL Solutions: prefabricated modular data center testing and certification Opened with curl. Identifies UL 2755:2025 as replacing the 2018 edition and describes integrated module evaluation and structural considerations. The proprietary outline itself was not accessed.
- NFPA: NFPA 70, National Electrical Code Opened with curl. Publisher listing for NEC editions, including 2026. Publication does not establish local adoption.
- California Building Standards Commission: 2025 Electrical Code errata and adoption history Opened with curl. The History Note Appendix confirms adoption of NEC 2023 with California amendments and the January 1, 2026 effective date.