Swinerton Mass Timber craft sets a clt panel

A large earthquake is expected by some experts to shake the Pacific Northwest within the next 50 years or so. The new Beaverton Public Safety Center now under construction is being engineered to withstand such a quake and continue operating thereafter.

Ground was broken in September 2018 on the three-story, 72,000-square-foot building on a 3.5-acre site at the junction of Southwest Hall and Allen boulevards. The center is being built by general contractor Skanska USA Building to an “essential facility” standard that calls for immediate occupancy and safe operation following a seismic event. Designers settled on a structural approach combining steel, mass timber and concrete.

“We’re using steel primarily to get our longer spans and reduce the column spacing on the interior,” said John Pete, project architect for FFA Architecture and Interiors.

However, use of cross-laminated timber floor and ceiling panels allowed removal from the design of much of additional steel that otherwise would have been needed. A three-and-a-half-inch concrete deck will be poured atop the CLT.

“The CLT goes in first and actually is the formwork for the concrete to be poured in on top of it,” Pete said. “That provides a lot of our seismic performance and ties our BRB (buckling restrained brace) frames together and provides a lot of the seismic stability.”

While seismically effective, the hybrid approach also increases the complexity of project management, procurement and logistics.

“Anytime you’re interfacing different types of materials,” said Derek Bourque, project manager for Skanska USA Building, “whether it be steel and CLT, steel and CMU, the more materials you mix the more challenging it becomes, in our opinion and experience.”

Currently, ironworkers are erecting structural steel for the building’s second floor. Carpenters from Swinerton Builders have been hired to fly in and install the CLT panels because of their expertise with this methodology.

“Typically when we build a steel structure we go three or four floors and then start decking our way up,” Bourque said. “But on this project we have to go up floor by floor, because we would trap ourselves and not be able to fly the panels in if we framed the structure up. And then just flying 10,000-pound-plus panels 40 feet long and getting them in position and trying to thread them between columns, it’s tough.”

Other building areas – almost exclusively those not facing the public – will feature concrete tilt panels and CMU (concrete masonry unit) wall construction. A slab-on-grade foundation will have an HDPE (high-density polyethylene) liner to keep moisture out.

The building’s interior will hold open office space, holding cells, storage areas, an employee gym, and an open lobby with a stair featuring exposed structural steel and precast treads and landings.

Interior finishes will include exposed CLT ceilings, architecturally exposed structural steel, acoustical paneling, finish carpentry, polished concrete flooring, interior glazing and gypsum assemblies.

The exterior façade will primarily feature masonry veneer with recessed vertical patterns. An aluminum-framed storefront and curtainwall glazing assembly will greet the public with glass and vertical wood slats, while exterior areas featuring tilt panels will also have inset metal panels.

The building is designed to be the new home of not only the Beaverton Police Department, but also the city’s emergency operations management department. To preserve operations after a sizable earthquake, the building must remain upright and functional.

As such, the center will have a 330 kilowatt rooftop photovoltaic array and an emergency diesel generator with underground fuel storage. Also, a micro-grid energy management system is being implemented to coordinate and control various power sources.

The new center will be a vast improvement over the police department’s current digs near Griffith Park, police Capt. Eric Oathes said.

“We’re at the Griffith Building right now, and it’s just a really old building that’s been remodeled time after time,” said Oathes, who is serving as the city’s project manager. “We wanted the open office concept to be able to have free flow throughout the building and bring all the units back together, and especially bringing the emergency management offices into it. They’re (serving) an important role in this as well, so we wanted to make sure that in the event when an emergency comes up and we have to activate the EOC, that we have the room and the facility to be able to meet the needs of the community.”

The building is scheduled for delivery in March 2020.

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