Photo courtesy of Reid Middleton Reid Middleton installed 56 friction dampers at 28 locations throughout Alaska Airlines' maintenance building.

Alaska Airlines’ SeaTac-based maintenance facility is critical to the airline’s regional and national operations. Crews use the facility to maintain and repair the airline’s aircraft fleet so departures around the nation are not delayed.

After the 2001 Nisqually earthquake, the airline commissioned a seismic screening and evaluation study of the building to ensure it would remain functional after the next major earthquake. The airline decided to go ahead with a seismic upgrade, but the facility had to remain open throughout the project.

Typically during an earthquake, the energy generated in a building is dissipated through the yielding of braced or moment frames, or the yielding of reinforced steel in shear walls. But these methods of dissipating energy can cause significant damage to structures.

So the structural engineer, Reid Middleton, designed a system using energy-dissipating seismic friction dampers — a series of plates tightly clamped together that absorb earthquake energy by rubbing together and generating heat, much like the brakes on a car dissipate energy in the form of heat. The dampers allow a building to move only in specific locations, dissipating energy through friction in the damper rather than damaging the rest of the building. This approach extends the useful life of the building, reduces its overall life-cycle costs and reduces the demand for natural resources that would be required to build new structures.

The dampers were placed where they could be installed quickly, minimizing the interruption to the building occupants.