6 minute read
UNBC researchers look to build better, quieter wood building
UNBC researcher Jianhui Zhou speaks about his research to reduce the amount to vibration and noise transferred through mass timber buildings on March 30. (Citizen photo by Arthur Williams)
Arthur Williams
If a $2,000 rubber ball falls from one metre onto a wood panel floor, will their downstairs neighbours hear a sound?
The heavy rubber ball, designed in Japan to simulate a typical human footstep, is just one of the tools that UNBC researcher Jianhui Zhou and his colleagues at UNBC’s Wood Innovation and Design Centre and Wood Innovation Research Lab downtown Prince George are using to study the acoustic and vibration characteristics of mass timber building materials. Zhou hopes the research he and his colleagues are doing today will help developers build quieter, more comfortable wood buildings in the future.
“Wood does not have a good reputation for sound insulation,” Zhou said. “Mass timber buildings use pre-fabricated wood panels. They are still considered lightweight building materials. They are a little bit better (for sound insulation) than stick framing, but not a lot more.” Zhou, who has been an engineering assistant professor at UNBC since 2018, thinks he can change that. And thanks to a nearly $250,000 grant from the Canada Foundation for Innovation’s (CFI) John R. Evans Leaders announced in March, Zhou and his team will have more than fancy rubber balls to prove it. The grant has allowed UNBC to purchase a state-ofthe-art sound and vibration data acquisition and analysis systems, vibration and acoustic sensors, a vibration shaker and laser vibrometer.
The team’s research is also supported by a Natural Sciences and Engineering Research Council of Canada Discovery Grant and a B.C. Forestry Innovation Investment Wood First grant.
The current system Zhou and his colleagues are using can only capture six channels of data at once. The new system will be able to record 24 different data streams at the same time, and can be expanded to capture more than 100, he said. That means the team will be able to get more information out of each experiment and do things – like track vibration and sound simultaneously – that they couldn’t before.
Zhou and his colleagues don’t just study the physics and material science of the building materials, they also have volunteers rate their subjective perceptions of floor vibration and noise – turning hard data into useful guidelines for what people living and working in mass timber buildings will experience.
Concrete, used extensively in large modern buildings, is not much better than wood when it comes to vibration and sound, “it just performs differently,” Zhou said.
A normal human footstep isn’t enough to get dense, heavy concrete to vibrate, he said. But when it comes to higherfrequency sounds, caused by things like a woman walking in stiletto heels, concrete actually transmits more sound and vibration than wood.
Wood frame or wood panel floors, however, transfer the lowfrequency vibrations and sound of people walking fairly easily, he said.
“Some people are more sensitive to that vibration,” Zhou said. “If we want to look at building medical buildings or laboratories out of mass timber… some of the equipment is very sensitive to vibrations. If you want to use wood to build a science lab, it is
UNBC researcher Jianhuis Zhou and his colleagues are studying mass timber construction building materials and methods at the university’s Wood Innovation Research Lab in downtown Prince George. (Citizen photo by Arthur Williams)
important to make a section of the floor which has almost no vibration.”
In their laboratories in the UNBC’s Wood Innovation and Design Centre and Wood Innovation Research Lab, Zhou and his colleagues are testing the performance of different types of wood panels and beams. They have also built a test room, with a dowel-laminated wood panel roof and framed-in walls to test ways to reduce noise transmission through walls and from one level to another.
Some of the practical solutions Zhou is studying include using insulated subfloors or concrete overlays to allow the finished wood to show on the ceilings, while still reducing sound transmission.
“We like to see wood, it creates this warm environment,” he said. “Using wood (instead of concrete) helps us lower our carbon emissions.”
It could also create economic opportunities for companies in northern B.C to produce wood panels for mass timber construction and build apartments, office buildings and other large buildings from locally-made products. While Zhou gave the Citizen a tour of the WIDC labs, one of his students was conducting material tests for a wood panel maker in Golden, B.C. “We’ve never gotten any (commercial) projects from northern B.C.,” Zhou said. “We haven’t had any interest from them.”
UNBC researchers would be eager to work with local forestry companies looking to develop new mass timber products. “We can do all kinds of work here, or testing.”
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