OREGON STATE UNIVERSITY

Mass timber is shaking things up

Researchers affiliated with the TallWood Design Institute tested a resilient, full-scale mass timber building constructed with cross-laminated timber (CLT) at the Natural Hazards Engineering Research Infrastructure outdoor shake table facility at UC San Diego in July, collaborating with researchers of the NHERI TallWood Project. 

The project, which tested performance of the structure through a series of simulated earthquakes, is the latest round of testing to develop and validate a seismic design methodology for eight-to-20 story tall wood buildings that incorporates high-performance systems and can guarantee structural integrity of the building both during and after an earthquake.

Along with other scenarios, testing of the two-story structure measured how shear walls counter the lateral loads produced by wind and earthquakes, using a technology called the rocking wall system.

In the rocking wall system, shear walls are connected to a steel footing utilizing post-tensioned, self-centering rods that run up next to the cross-laminated timber (CLT) wall and special u-shaped brackets on the side. The rods allow the wall to rock laterally during an earthquake and snap back into its original upright position afterwards, minimizing the impact of these natural occurrences and the resulting structural damage to the building.

In addition, this project measured the performance of CLT composite floors used as a diaphragm.  A diaphragm is a structural element that transmits lateral loads to the vertical resisting elements of a structure, such as the shear walls mentioned above. There is very little information in the United States regarding use of CLT as a diaphragm. The results of the testing will provide benchmark data needed to develop building design guidelines for this structural use of CLT.

Arijit Sinha, associate professor of renewable materials with the Oregon State University Department of Wood Science and Engineering, and Andre Barbosa, assistant professor of structural engineering and Chris Higgins, professor of structural engineering with the OSU School of Civil and Construction Engineering, lead the test of the building, which is 22 feet tall and has 20-by-60-foot CLT floors.

The TallWood Design Institute is the nation’s only research collaborative that focuses exclusively on the advancement of structural wood products.  It is a partnership between Oregon State University and the University of Oregon, bringing together the strengths of OSU's College of Forestry and College of Engineering, and the University of Oregon College of Design.