By Patrick McLaughlin
Managers of data centers or other computing centers who must factor seismic protection into their everyday planning face specific and sometimes daunting considerations. As we reported a little more than a year ago (“Seismic-activity preparation requires care in product selection,” September 2015), the International Building Code (IBC) incorporates ASCE 7 Minimum Design Loads for Buildings and Other Structures, which was developed by the American Society of Civil Engineers (ASCE). ASCE 7 includes guidelines and calculations intended to prevent nonstructural components from sliding or overturning in an earthquake.
The IBC separately categorizes facilities and components/nonstructural elements, based on the earthquake-related risks associated with them. Data centers rank highly, as in high-risk, among facilities. Equipment like network cabinets and racks are rated as components/nonstructural elements.
Of note, the state of California has its own set of codes-the California Building Code-that incorporates much of the IBC’s content but also includes specifications particular to state laws.
Regardless of its location, a data center that has to be prepared for potential seismic activity also faces many of the same challenges that data centers everywhere face-including thermal management.
In a post to Upsite Technology’s blog earlier this year, critical facilities consultant Ian Seaton weighed in, with heavy detail, on the practicality of achieving both seismic preparedness and thermal management. Seaton began the blog post, titled “Achieving data center containment through seismic requirements,” by stating bluntly, “Conventional wisdom is pretty clear that when it comes to a choice between saving a buck and saving your butt, anatomy takes precedence.” For that reason, he says, when a data center is located in a seismically active area, “prudence, and sometimes relevant building codes, typically guide us to focus our energy on designing and building a data center that will stay put on shaky ground and lose sight of the airflow containment strategies that help our operating dollars stay put as well.”
It doesn’t necessarily have to be that way, he asserts, to the tune of about 1500 words. This article will paraphrase and excerpt some of Ian Seaton’s teachings on the coexistence of containment and seismic readiness.
“Not only are seismic considerations no reason to compromise on airflow containment best practices; there are situations in which such compromises are not even allowed,” he explains. “In California there are very stringent requirements for the seismic sturdiness of data centers in hospitals and other life-safety-critical applications. These requirements are defined and enforced by the Office of Statewide Health Planning and Development (OSHPD).”
He adds that, “California Administrative Code, Chapter 6, Table 11-1 defines that all communications systems in an NPC-2 building must be braced or anchored in compliance with Part 2 of California Title 24 … Part 6 of Title 24 dictates that there must be a physical barrier between the supply air mass and return air mass in all data centers with an IT load in excess of 175kW such that the heat load removal path inside the IT equipment is the only path between those two air masses. Data center seismic robustness and energy-efficient airflow containment are therefore required by the same umbrella government regulation.”
Seaton acknowledges that, of course, data centers are built outside of California, and therefore not subject to the regulations that make both seismic readiness and airflow containment a matter of law. In those places, the aforementioned IBC and ASCE documents prescribe. Then, Seaton says, “Once a seismic requirement has been established, the next question addresses how to both meet the seismic requirement and derive the airflow containment benefits.
“Seismic isolation might be the easiest path,” he continues. “If a building were supported on columns equipped with friction pendulums, the entire building could effectively float above the earthquake movement. This isolation would essentially allow the data center located within such a building to look like any other data center with standard server cabinets and any of the traditional hot-aisle containment, cold-aisle containment, or chimney cabinet airflow separation topologies.”
He adds that partial isolation-isolating individual or groups of server cabinets-may also be a possibility, albeit with complications including “the potential instability of the large return hot aisle duct” precluding hot-aisle containment.
Seaton also offers up the use of preapproved seismic hardware as an option. When taking this approach, he advises, one should “begin with as many preapproved seismically ruggedized pieces of hardware as can be specified that meet the rest of the application performance requirements. One possible starting point would be GR-63 CORE-compliant server cabinets. Such cabinets have been tested on a shaker table under extreme motion conditions and not only have survived, but have performed under a tight deflection threshold that assures the survivability of components mounted within and accessories attached externally.
“Another source of hardware that will offer a little more flexibility and variety will be the OSHPD Pre-Approval of Manufacturers’ Certifications (OPM) list,” according to Seaton. The list is available on the oshpd.ca.gov website. “This list will not only include server cabinets from multiple vendors, but it will include associated pathways and other ancillary accessories, with bills of material and instructions for anchoring and bracing.”
He pointed out that at the time of his post in January, the OPM lists did not contain containment products “primarily because they are so typically application-specific, so this is where a structural engineer gets involved with the project to use IBC methodology to certify design-specific elements.” He later emphasized that the key “is to start with GR-63 CORE or OPM components that have been seismic certified and then have the containment additions certified on-site, which will likely require additional anchoring and bracing tactics, which should also be a part of that engineer’s expertise.”
In conclusion, Seaton notes, “The available options for incorporating airflow containment within a data center that meets some level of seismic withstanding compliance means that there really is no good reason for compromising on airflow management.”
Patrick McLaughlin is our chief editor.