Nepal 2015—Japan 2011—Chile 2010.
In the past decade, these nations, and many others, have been host to some of the most destructive earthquakes in recent memory. Along with the inestimable human and emotional toll these events take on communities around the globe, the costs associated with reconstruction efforts are equally astronomical, often edging into the billions of dollars. Although we can’t effectively predict or stop earthquakes from occurring, we can be ready, and minimize the impacts of these damaging seismic events.
CLT concept and use in a nine-story mid-rise building in London.
From relatively stable ground in Madison, Wisconsin, researchers at the Forest Products Laboratory (FPL) are searching for better ways to build more resilient, taller, safer, and cost effective wooden structures for use in earthquake-prone areas of the nation. For the wood building community, the most viable tall building construction solution incorporates the use of cross-laminated timber (CLT).
A CLT panel consists of multiple layers of kiln-dried lumber boards stacked in alternating directions, and bonded together with structural adhesives. The end result is an inexpensive, strong, solid, rectangular panel that can be used for building walls, floors or roofs.
CLT has already established itself as an important building material in Europe, but is relatively new to North America. Wooden buildings over eight stories tall, which incorporate CLT into their design, have sprung up in areas of low seismic activity to include Sweden, Australia, and the United Kingdom. Experts believe that CLT could also be a cost-effective and environmentally friendly alternative to traditional construction materials for buildings up to 125 feet tall.
FPL, along with the Coalition for Advanced Wood Structures, is developing seismic design perimeters for CLT use that will meet or exceed both design and safety codes. The team hopes that the project will lead to the development of a performance-based seismic design (PBSD) methodology to investigate the feasibility of three prototype systems. This PBSD would allow for the construction of buildings in earthquake-prone areas up to 14 stories tall using CLT components.
Researchers believe that this project will lay the ground work for buildings with elongated natural periods, near elastic behavior, and an increased resiliency to the high forces and accelerations of seismic events.
The growing trend of urbanization has increased the need for taller buildings across the country, including in areas that are crisscrossed by tectonic boundaries like California’s San Andreas Fault or the Cascadia Subduction Zone of the Pacific Northwest. At the same time, more emphasis has been placed on environmentally and fiscally responsible construction. Properly rated CLT construction holds great potential for cities like Los Angeles or Seatte—urban areas that have already witnessed tragedy in the past, but hopefully, when and if the next disaster occurs, can be headline-making cities for their successful implementation of safer building techniques.
For more information on, see this Research In Progress report.