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Bently builds to withstand seismic activity

by Linda Hiller

Following the devastating damage and tragic loss of life precipitated by the recent earthquake in Turkey, it is no wonder that people in world communities are asking themselves, “Could it happen here?”

The Carson Valley is no exception, but one resident and business owner has been contemplating earthquakes for much longer than just the last week.

Don Bently, founder and head of Bently Nevada Corp., with more than 900 local employees, has been building some of the safest structures in town for years.

“Sure, it costs some extra money, but it is worthwhile for the safety,” Bently said, adding that he considers it an investment in the future. “My philosophy is to make long term plans – for the next century.”

The plans for Bently Nevada Corp.’s new 3-story, 54-foot tall, 280,000 square-foot headquarters off Buckeye and Orchard roads include design details that will make the structure safe to a Zone 4 earthquake region, plus a 25 percent safety margin on top of that. The Carson Valley is a Zone 3 earthquake region, and that is what the county building code requires new construction be built to withstand.

n Joints that move are key. The new Bently building has a steel frame with bolted construction designed to allow the joints to slip and give in the event of an earthquake, according to the building’s structural engineer of record, Vance Gabbart of Gabbart and Woods in Reno.

“The Bently headquarters is designed and built to the same standards as would be required of an essential facility, such as a hospital, in the middle of San Francisco,” Gabbart said.

There are many designs for buildings, especially tall or large structures, which are geared toward keeping them safe during an earthquake. The key is to make movement possible so when the earthquake hits, the building can “go with the flow,” rather than stiffly resist and (possibly) snap and crumble.

This unique bolted design, called BDMF, or “bolted ductile movement frames” construction, was refined after the 1994 Northridge, Calif., earthquake, and simply allows for more give and play at the steel beam joints.

The technical skill involved in framing a 250,000-square-foot building with flexible joints is mind-boggling, according to project manager, Ken Forbes.

“The whole thing has to line up within one-fourth inch,” he said. “Because everything is bolted, with 60 bolts per joint, we can’t have much error. You can’t just bend these beams into place.”

Forbes said 60 bolts are inserted into oversized bolt holes where the joint gets its “give,” torqued and tightened at each joint.

The new headquarters building, which will house 1,000 employees, also has enough back-up generating capacity to run the entire operation indefinitely, according to Bently marketing manager Steve Sabin.

Bently’s project manager, Ken Forbes, a mechanical engineer, said bringing the building from the required minimum of Zone 3 to Zone 4 plus 25 percent, has cost a considerable amount more in just the steel.

“I’d say we used an extra 400 tons of steel in the oversized beams alone,” Forbes said.

n Youthful impression. Bently, who will be 75 in October, said that although he grew up in the Midwest and didn’t have to face earthquakes as a child, he did have a memorable experience with an earthquake when he moved to Los Angeles around 1951.

“I was taking apart a chicken coop for my landlord, and I took off the front frame first and the earthquake hit,” he said. “I think it was around a 6.5 – I do remember that it was a heavy earthquake and rolled back and forth. There wasn’t particularly major damage, but it impressed the hell out of me.”

Bently said frequent earthquakes around the Mammoth, Calif., area have also been an inspiration to him in building Bently Nevada Corp. structures that are safe from earthquakes.

“Fundamentally, the recent happenings in the last 15 to 20 years in Mammoth, have been a concern,” he said. “That area has been know to be a seismically active area, with some talk of a volcano eruption, and Mammoth isn’t that far away.”

Taking a risk. One of the downsides to “earthquake-proof” building construction is the possibility that following the “big one,” the frame could be compromised to the point where it might not be safe.

Forbes said that would take a quake even larger than the recent one in Turkey – probably up to an 8.0 on the Richter scale – to cause the steel joints to be permanently damaged beyond repair. Following any earthquake, the structural connections will be thoroughly inspected, he said.

During the last several years, Bently has also overseen construction on other Valley buildings that needed earthquake retrofitting, including the Minden Wool Warehouse in 1997 and the Bently Training Center at the Science Park last year.

Bently, whose company employs more people in the Carson Valley than any other employer, said he hopes all his projects provide a safe haven.

“Unfortunately, people have short memories,” he said. “The earthquake tragedy in Turkey is fresh in our minds now, but in a few weeks most of us will have forgotten about it, unaware of the risks that exist locally.”

The new Bently Nevada Corp. headquarters – safe from earthquakes to Zone 4 and beyond – is scheduled to be completed by the end of this year, with employees in there by January 2000.