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In order to realize the full potential of cross-laminated timber, researchers at Portland State University are working to prove new applications of the building product can stand up to earthquakes.

Their guinea pig: the Framework tower planned for the Pearl District.

The wooden skyscraper being developed by project^ and designed by LEVER Architecture is awaiting permits so that crews can begin a planned 14-month construction effort. The project team believes it’s among the vanguard of a revolution in sustainable construction in the U.S. But many boxes have had to be checked to get to this point.

To gain approval under current building codes, project members 鈥� including a team of structural engineers with KPFF 鈥� have had to prove product concepts relating to fire and life safety, acoustics and seismic resilience.

Much of the testing for the latter has taken place in the bowels of the science hall at Portland State University 鈥� at the iSTAR (Structure Testing and Applied Research) lab.

There stands a full-scale mock-up of a corner of the Framework building. PSU graduate student Tyler Williams has been studying the seismic strength of different applications of the innovative building product. The current one features a connection of glue-laminated beam and glue laminated column with a panel of heavy CLT on top.

鈥淲ith our project, we think the most important thing that we’ve able to demonstrate is that these connections can experience quite a bit of displacement and be rotated quite a bit from a simulated earthquake motion and still carry the gravity loads,鈥� he said.

Two years ago, Williams was nearing completion of his bachelor’s degree at PSU when he learned about research led by PSU civil engineering professor Peter Dusicka that was being funded by the National Science Foundation. Williams was able to transition directly to a graduate program, and research seeking to validate some of Framework’s mass timber concepts.

The chance to work at the cutting edge was alluring to Williams.

鈥淚t’s something new to work on,鈥� he said. 鈥淭ypically when you’re doing research on building materials like this, you’re doing work on a known quantity, and you’re trying to apply it in a different way. But nobody’s ever built a project like Framework.鈥�

The iStar lab is jam-packed with actuators, concrete formwork and, in the middle of the room, a shake-table capable of replicating the speed and intensity of 鈥渁ny鈥� earthquake, according to Dusicka.

Until last year, the lab tested virtually only products related to Oregon Department of Transportation projects. But the $400,000 NSF grant enabled mass-timber testing, including specimens of Oregon-made CLT from the state’s lone manufacturer, DR Johnson in Riddle. (There’s now one other certified CLT manufacturer in the U.S., in Montana.)

With the Framework testing now winding down, Williams, Dusicka and the other research team members have begun looking for new ways to connect CLT and glulam. Essentially, they want connections that do more with the least amount of material.

Another CLT project proposed around the same time as Framework has sped ahead in recent months and rushed out of the ground. Design-build firm PATH Architecture last month topped out its Carbon12 project on North Williams Avenue (with Gov. Kate Brown in attendance). This project employs a simpler structural system 鈥� a hybrid employing CLT for the floors and lateral steel.

Dusicka said Carbon12’s system, though innovative in its own right, represents a transitional step between traditional concrete-and-steel construction, and full-on mass timber, like Framework’s.

Glulam has been around for a long time. But the advent of CLT has meant more possibilities for wood as a structural component of tall buildings. The trick so far has been finding the right way to use CLT, Dusicka said.

Northwest residents are beginning to expect their buildings to be occupiable after a large event.

鈥�(CLT) has lots of benefits, but also has lots of barriers,鈥� said Dusicka, who’s been at PSU for 12 years. 鈥淚f developers don’t care about this (research), they should. Without this research, they can’t move ahead with the code approval process. We’re essentially giving them tools for construction in the physical world.鈥�

Similar testing is occurring at Oregon State University and other institutions in the West. With the bulk of Williams’ Framework-related research now wrapped up, his group will perform several independent tests and write papers based on their results. He plans to graduate in June, and find a job in the private sector as a structural engineer.

鈥淭here seems to be a lot of positivity right now about validating this,鈥� Williams said. 鈥淚 think there’s definitely an appetite for it.鈥�