Quake-Proof Engineering
Author: Stephanie Argy
Posted: June 6, 2017

Preparing Oregon for the big one

WHEN Peter Dusicka and his team of researchers go to work each day, they confront a difficult challenge: finding ways to help the Pacific Northwest prepare for earthquakes with infrastructure built under the premise that there would be none.

For more than a century and a half, people believed the Pacific Northwest was a seismically inactive part of the world. Buildings, bridges, highways and the power grid were constructed with the assumption that they would never be threatened by earthquakes. The region is filled with concrete and unreinforced masonry structures that don’t do well when shaken. Only in the late 1970s and early 1980s did geologists, historians and seismologists make the discovery that the Pacific Northwest is in fact extremely dangerous, seismically speaking.

Piecing together clues from many different disciplines, researchers deduced that on January 26, 1700, the coast of northern Oregon and southern Washington was struck by a 9.0 earthquake, which in turn generated a tsunami recorded in Japan 10 hours later. Further research indicates that northern Oregon experiences a quake of that magnitude roughly every 350 years, and there’s a 20 percent chance that the region—including Portland—will be hit by an earthquake of 8.0 or higher within the next 50 years.

What happens to our built environment in the event of such a cataclysm? Engineering professor Dusicka and his team have two main focuses: first, to help the existing infrastructure, especially bridges and high-voltage power, survive a massive earthquake, and second, to devise approaches to engineering and construction that will result in resilient, sustainable new structures.

“Our built environment is already there, and we have to live with what we’ve got,” says Dusicka, civil and environmental engineering faculty in the Maseeh College of Engineering and Computer Science. To that end, his lab collaborates with the Oregon Department of Transportation to help determine the seismic vulnerability of more than 2,000 highway bridges in the state, and with the Bonneville Power Administration to retrofit their critical equipment.

“Our relationship with PSU has been very long and historic, and we’ve solved a lot of problems together,” says Leon Kempner, Jr., principal structural engineer with the Bonneville Power Administration, which has facilities in Oregon, Washington, Idaho and western Montana. “We have a large system that is vulnerable, based on today’s hazards.”

DUSICKA’S LAB, the infraStructure Testing and Applied Research (iSTAR) lab, has a large platform that can reproduce the shaking of real earthquakes. It’s been used to test equipment and battery racks, flexible conductor links and seismic dampers for Bonneville.

“It’s difficult for us to shut the system down to do that kind of work,” says Kempner. “The devices we’re developing in general are meant to be installed while the system is energized.”

Kempner says that the Bonneville Power Administration’s current project with iSTAR lab involves developing damping devices using deformable plates that can absorb shocks during an earthquake.

“They did the research for designing the device, and now we’re asking Dusicka’s team to help implement it,” says Kempner. “We’re having them work on an installation—near Oregon City—where we’re concerned about seismic vulnerability. It’s a unique task that they’re doing: taking it from the research to the implementation. That’s not usually done at the university level.”

The other part of Dusicka’s work involves planning for the future by coming up with innovative construction methods for new buildings. “We’re looking at ways to make structural systems out of mass timber that are seismically resilient,” says Dusicka. Mass timber uses new technologies to compress and laminate multiple layers of wood, so that this material can be a sustainable alternative to steel or concrete for large building construction.

Dusicka is collaborating with the designers of Framework, a 12-story all-mass-timber building that is going up in Northwest Portland. Although there are many buildings that use mass timber in some form, there are only about 12 in the country built entirely out of mass timber and none higher than Framework.

The Framework project won the U.S. Tall Wood Building Prize Competition, which provided $1.2 million to fund the exploratory phase of the project, including research, development and project-specific tests. The engineering firm working on the project, KPFF, has been using the iSTAR lab to subject the building’s beam-to-column connections to the kind of movement they might undergo in a seismic event. “We want to make sure that the connection won’t tear itself apart in an earthquake,” says Eric McDonnell, an associate at KPFF.

AN EXCITING feature of mass timber, says McDonnell, is the promise that buildings made from it could be repaired after an earthquake and thereby have a longer lifespan, an important consideration when assessing the sustainability of a building. Standard earthquake code ensures that people within a building survive, not that the building ever be usable again or might be possible to repair.

After Christchurch, New Zealand, was struck by a massive earthquake in 2011, over 100 buildings had to be demolished. “Not because they failed,” says McDonnell. “They performed up to the life-safety objective that was required of them: People were able to get out, but a number of the buildings weren’t economical to repair.”

Dusicka, who spent time in New Zealand after the Christchurch earthquake, says the country is actively pursuing the means to become more resilient. “On infrastructure and building, they don’t mind experimenting with innovative systems in search of improved performance. They learned that lesson the hard way.” In the United States, he does not find the same openness.

“It’s a lot harder to introduce new technologies into practice. But recently, I sense that people in Portland are starting to get it. They’re starting to understand that there is a potential risk,” says Dusicka. “I feel that Portland State and some of the work we do are making an impact. Being an urban campus and being part of the community does help us in terms of having our recommendations heard.”

Stephanie Argy is a graduate assistant in the Office of University Communications.

Caption: Engineering professor Peter Dusicka in the campus iSTAR lab. Photo by Kelly James.