Buildings made from wood have long provided a warm, aesthetically pleasing atmosphere, while appealing to real estate investors trying to reduce their carbon footprint. Now, results from a new research project show wood buildings have another benefit: they may fare just as well astraditional construction in earthquakes.
An experiment started a few months ago at the University of California, San Diego involving more than 40 corporate and academic professionals is indicating that high-rise timber buildings are able to resist violent shaking. Tests on a 10-story timberstructure, called TallWood,built for the project on the campus so far find a greater degree of earthquake resistance than expected.
“We were expecting some sort of damage but what we have observed is that this is the most boring test ever,” said Shiling Pei, a civil engineering professor at the Colorado School of Mines leading the San Diego experiment. “Nothing breaks” even when subjected to the most intense earthquake simulations, he said, adding that more testing is planned for later this summer.
These early findings are significant for the commercial real estate industry because of the increasing popularity of structures made mostly from timber in the United States. Architects and engineers are seeking to expand the use of timber as building codes change and taller timber structures are built.
The type of timber used in building projects known as mass timber, which refers to several different types of engineered wood products, comprises planks of treated wood — typically spruce, fir or pine — attached to each other by glue or other adhesives. The finished product has strength and fire-resistant characteristics that are equal to concrete and steel.
Architects, construction and engineering firms and private timber companies have been striving for years to design buildings with ever-higher proportions of mass timber and lower amounts of steel and concrete.TallWoodis the highest building made primarily from mass timber ever tested anywhere in the worldfor large-scale earthquakes, according to Dan Dolan, a civil engineering professor at Washington State University who is participating in the experiment at UC-San Diego.
Even with buildings like TallWood where the floors, walls, ceilings and framing are all made from mass timber, some concrete and steel is still used in areas like the foundation or in anchors, fasteners, nails and screws.
The buildings still have hurdles to overcome, including in terms of total costs, proving their strength, and winning over the insurance industry. But the tests are showing the areas where improvements could be made.
Lateral Stress Testing
The TallWood experiment involves placing the structure on a movable platform, called a shake table, that simulates earthquake conditions. The National Science Foundation provided $2 million in grants to help fund the design and construction of the test building, which is expected to be torn down once the experiment is complete. Timber companies and universities are also supporting the project through funding and research, though the organizations providing funding have not been disclosed.
The San Diego experiment is notable because it examines the ability of masstimber to handle lateral-direction stresses caused by earthquakes, according to structural engineer David Cocke. Lateral systems are typically made from concrete and steel.
“It’s got real potential,” Cocke, principal and founder of engineering firm Structural Focus, told CoStar News. “You will need to convince planners that it’s viable, but I do think some version of mass timber lateral systems will happen.”
The global push to combat climate change and related popularity of wood buildings is likely to create more demand for new mass timberconstruction, said William Silva, director of pre-construction at Swinerton, a national construction company that is providingengineering services for the San Diego research project.
And much of the surge could happen on the West Coast in some of the world’s most notable earthquake hot spots.
As the technology has advanced in the production methods of mass timber, architects and construction engineers have been able to use more of it in building designs. It helps that mass timber ismore flexible, or ductile, than traditional building materials.
“Wood has better ductility than concrete or steel,” Jonathan Heppner, a partner at Lever Architecture in Portland, Oregon, told CoStar News. That “allows it to deform and flex during a seismic event without failure.” Heppner and his firm served as lead architects for the building used in the San Diego earthquake test.
It takes less carbon to produce mass timber than concrete and steel, Mark Oberholzer, principal at architecture firm KTGY, a creator of mass timber designs, told CoStar News. That makes mass timber buildings more appealing to real estate investors.
“A building that uses a lot of energy or was built from materials that required a lot of energy has a lower value,” Oberholzer said.