Building a Better Understanding of Mass Timber

By: Josh Kulla in Oregon Daily Journal of Commerce | April 13, 2021 1:58 pm

Tradespeople and engineers might be surprised by how much they can teach each other.

That was one of the key takeaways from a recent pilot program hosted by the Tallwood Design Institute last month at Oregon State University in Corvallis. OSU staffers led Northwest Carpenters Union apprentices through a mutually beneficial workshop that provided the latter with practical mass-timber construction experience and the former with a greater understanding of the building industry’s needs.

“It was just wonderful; it was a really great experience,” OSU assistant professor Erica Fischer said. “We’re hoping we can continue this, and this was 100 percent a pilot – a dummy test – to see if this could work. But I think that the carpenters enjoyed hearing about the bigger picture of what we were testing, and from the student perspective, understanding the questions the carpenters would ask. It’s something you can’t teach.”

The Tallwood Design Institute (TDI) is a collaboration of OSU’s colleges of engineering and forestry and the University of Oregon’s College of Design. The TDI provides prototype and testing services to the construction industry, and this pilot program is specifically being used to test structural connections between glue-laminated beams and columns.

Because of the size of the beams, columns and cross-laminated-timber panels involved, Fischer and others at OSU believed it would be wise from a safety standpoint to enlist the help of carpenters. But instead of simply hiring a contractor, officials used connections at the Northwest Carpenters Union and its training center in Tangent to find the help they needed.

“We need the constructability part of the research because we are testing new connections no one has ever used in a building before,” Fischer said. “We want to make sure we’re actually designing something that enhances the constructability of mass timber, so we felt having skilled laborers who might be the ones on the jobsite building this would be wonderful.”

Union representative Trampas Simmons helped organize the program and said apprentices were chosen based upon their previous experience working on mass-timber projects, including OSU’s Peavy Hall built by general contractor Andersen Construction.

“It’s great training for our apprentices,” Simmons said.

Experienced supervisors were brought in to oversee the work as apprentices built six structural specimens over a three-day period in February. The field work was combined with classroom instruction that informed apprentices of the much higher level of preconstruction preparation and planning required for mass-timber projects.

“Framing is kind of like a common knowledge of standards – it’s been around for a long time,” said instructor Brian Zeller, a superintendent with Corvallis general contractor and union signatory TGC Structural. “With mass timber it’s a process that’s different. You’re working with screws, hangers and large chunks of wood. Just as tilt-up construction is different than framing, CLT or MPP (mass-plywood panels) is even more different in itself. It’s unique in a lot of ways, but it’s still a process – but a process that is different. The plan is different and it makes or breaks you.”

After two days in the classroom going over CAD drawings created by OSU graduate research assistants, the apprentices headed into a lab to build the specimens. Each was pieced together using 12-foot-tall glue-laminated columns and 14-foot-long glue-laminated beams with 4-foot-by-14-foot CLT panels secured on top of the beams.

“It wouldn’t be built like it would be in the real world; it was built laying on its side,” Simmons said. “It was a giant learning curve, and for this portion it was mainly about rigging and trying to problem-solve. Our training center does have a CLT curriculum that will reinforce what they actually learned.”

“The exposure is 90 percent of the training,” Zeller added. “It’s the exposure to the plan, being part of the team, knowing your role and knowing the new connections. They’re just different than what we’ve done before. You’re dealing with a three-inch deck that’s one big piece.”

Once the six specimens were built, they were lifted upright by crane for initial testing of the structural connections. Over the next two months each specimen will be tested by applying lateral forces via a hydraulic actuator. The actuator will impose deformations that would occur during an earthquake.

OSU College of Engineering graduate assistant Haley Madland helped with the initial construction drawings for the specimens and will help facilitate testing in the coming months. The experience has been invaluable, she said.

“I’m a young engineering student,” she said, “and I have had chances to create drawing sets, but I’ve never been able to be there while they are being constructed. The feedback was great to know what translates well from design to construction.”

Both OSU and the Northwest Carpenters Union hope this is only the beginning of collaboration.

“We’ve been talking to the (union) for a while more generally about workforce development,” said Iain Macdonald, director of the TDI. “They are obviously interested in mass timber. It’s a new paradigm in construction in some ways, and because of the high level of prefabrication, they’ve been interested in training their members on that.”

Macdonald noted that OSU has also created for engineering students a new mass-timber construction course that combines the knowledge within the colleges of forestry and engineering. Collaboration with the union, he added, is just another offshoot of OSU’s effort to advance the technology.

“We are looking at ways to join forces and help each other out in that kind of training,” he said.

Did You Know?

PNWRCC has many women in our crafts and leadership positions.

Margaret Ellings became the first woman initiated into the United Brotherhood of Carpenters in October 1935. The establishment of a women’s committee within the United Brotherhood of Carpenters is one of the most important developments in the union’s recent history. Visit


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