Taking Earthquake Protection to the Next Level in Data Centers

Oct. 29, 2019
RagingWire/NTT is creating a base isolation system to provide an extra layer of earthquake protection for its Santa Clara data center. A primer on base isolation, how it works, and why these systems are rare at U.S. data centers.

SAN FRANCISCO – Should data center operators create more facilities with advanced earthquake protection? If they do, will customers pay a little more to improve earthquake defenses for their IT infrastructure?

The topic is especially relevant to data center operators on the West Coast, where three major data center markets – Silicon Valley, Los Angeles and Seattle – have a history of destructive earthquakes. Despite the mission-critical industry’s focus on risk, building-level earthquake protection systems are rare in the United States.

Those questions are at the heart of a new project in Silicon Valley, where RagingWire/NTT is creating a base isolation system to provide an extra layer of earthquake protection for its first data center in Santa Clara. The decision is influenced by NTT’s experience in Japan, where base isolation is commonly used in high-rise buildings in urban areas.

There are about 9,000 buildings in Japan that use the advanced earthquake systems. But the story is very different in the U.S., where only about 175 buildings are equipped with base isolation, a discrepancy explored in a recent story by The New York Times. They include the new Apple headquarters in Cupertino, Calif. along with Los Angeles City Hall.

In nearly 20 years covering the data center industry, I’ve encountered only one data center in the United States with a base isolation system – the 365 Main facility in San Francisco. To get a fuller understanding of earthquake defense in data centers, we’ll review system installed at 365 Main, and the plans for the RagingWire/NTT facility. But first, some background on trends in earthquake protection.

The Risk Equation in Earthquake Protection

Although Japan mandates strong earthquake defenses, governments in the U.S. leave the choice to real estate developers. America has long maintained stronger building codes than many other countries, and had fewer seismic catastrophes in recent years. As a result, earthquake disasters can be viewed as rare events, with a different risk frequency profile than other disasters. These systems involve additional cost, and most builders opt not to invest additional funds to add base isolation systems, despite the awareness of the potential that a “Big One” is a possibility.

“We seem intent on creating buildings with a minimal level of protection,” said Bob Woolley, Senior VP of Operations for RagingWire/NTT Data Centers. “People often don’t really understand the risk from earthquakes. They have a false sense of security. In the world we live in, people never take the risk until something happens.”

Woolley said that California building codes are designed so that buildings will remain standing, but can move quite a bit during an earthquake. That’s an issue for a building filled with racks of servers and power equipment instead of offices.

“Our intent is to create a building that not only keeps people safe, but keeps the equipment safe inside it,” said Woolley. “You have to create space for the building to move.”

U.S. data center companies that are concerned about earthquake risk typically adopt rack-level isolation units, which are installed under racks and cabinets and employ a ball-and-cone system to allow the equipment to gently roll back and forth during an earthquake. Worksafe Technologies has been a leading vendor of these systems.

Providing earthquake protection at the building level involves similar concepts, but a lot more engineering. Let’s take a look at base isolation systems and how they work.

Earthquake Protection at 365 Main

San Francisco is home to a vibrant tech community, but experienced widespread devastation from a 1906 quake and sustained another big hit in the 1989 Loma Prieta (“World Series”) earthquake.

In 2000, colocation provider AboveNet acquired a former tank factory at 365 Main in San Francisco. The structure is built atop a chunk of bedrock on Rincon Point that supports the pillars of the Bay Bridge (which runs alongside the site) and outside the liquefaction zones were earth is likely to be displaced by an earthquake. We recently toured the building with the team from Digital Realty, the current owner and landlord.

During its $130 million retrofit, AboveNet opted to go the extra mile by installing a seismic base isolation system. The system is visible in the facility’s underground parking garage, where each of the 94 columns supporting the building are equipped with a special joint known as a “friction pendulum” consisting of a plate and rubber bearings that absorbs the shock created by seismic movements.

The base isolation units are visible at the top of each of the 98 columns supporting the building, which can be seen in the underground parking garage. (Photo: Digital Realty)

In an earthquake, this will allow the entire building to effectively float above the shifting ground beneath it. The isolator is typically a sandwich of rubber and steel plates, and at 365 Main, they allow columns to sway as much as 15 inches in either direction

The piping, cabling and utility connections join the building above the isolation joints to protect their integrity in the event of an earthquake.

The base isolation units sit atop each pillar in the 365 parking garage. (Photo: Digital Realty)

The earthquake engineering extends outside the building, which is surrounded by an 18-inch wide “seismic moat” that will allow the sidewalk areas to fold and absorb the shock of a large quake.

Earthquake Protection at RagingWire, Santa Clara

As the U.S. data center business of NTT, RagingWire is part of an organization that takes earthquake risk seriously. A number of the company’s data centers in Japan are in high-rise buildings in urban centers, and equipped with base isolation systems. RagingWire has often noted that its data center campuses in Sacramento are in a more seismically stable location than the San Francisco Bay Area.

When it bought a 3.3-acre site in Santa Clara last year for its first facility in Silicon Valley, RagingWire/NTT began working with Paradigm Structural Engineers to create a base isolation system for the four-story, 16-megawatt data center.

“Our goal was to provide the maximum amount of protection,” said Woolley. “This is the right thing to do. We also thought this would be interesting to customers.”

A diagram showing how base isolation allows a building to move in either direction during an earthquake. (Image: RagingWire/NTT)

Woolley said that designing the system means balancing several design options in determining how much movement to allow. “The superstructure undergoes 60 percent less motion than a non-isolated fixed building,” he said. “There is some motion, but it’s far less than without the base isolation system.”

Isolator systems can be designed to experience movement ranging from two feet to five feet. Designing for additional motion will require larger isolators. RagingWire/NTT is using triple-friction pendulum (TFP) bearings, which will be about 6 feet in diameter. The system will also include viscous dampers, which provide passive energy dissipation by passing a piston through a shaft filled with viscous fluid, similar to shock absorbers. At the Santa Clara building, these dampers will limit the range of motion to 32 inches in either direction.

Woolley said the system isn’t designed for a particular magnitude of earthquake. In structure protection, the key issue is the duration of a seismic event.

“An earthquake that lasts a short period of time is a very different event from one that last a long period of time,” said Woolley.

The additional earthquake protection required investment by RagingWire/NTT, and that may be reflected in slightly higher leasing rates. Woolley believes Santa Clara is the right market to offer this product to the market.

“In this building, it’s probably $5 million (in additional construction costs),” said Woolley. “We hope we’ll find customers that value the additional protection. There’s a premium for it. We’re in a competitive market here, but it’s not a 60-megawatt building, it’s a 16-megawatt building. We’re betting that there are 16 megawatts worth of customers willing to pay a slight premium.

“It’s not a play where we think we’re more profitable because we have a better widget,” he added. “We think it’s the right thing to do for customers, and people will find value in it.”

About the Author

Rich Miller

I write about the places where the Internet lives, telling the story of data centers and the people who build them. I founded Data Center Knowledge, the data center industry's leading news site. Now I'm exploring the future of cloud computing at Data Center Frontier.

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