UPDATE: US Army tests CLT shelter to withstand one-in-250-year earthquake

UPDATE: This story originally ran on Nov. 18, 2024. It has been updated to include additional information on the CLT B-hut.

The U.S. Army tested a cross-laminated timber (CLT) shelter made using thermally modified Coastal Western Hemlock. In the seismic testing in Champaign, Illinois, the shelter reportedly withstood shaking that simulated a 1-250-year earthquake.

The testing by the US Army Engineer Research and Development Center (ERDC) Construction Engineering Research Laboratory (CERL), in collaboration with the Composite Recycling Technology Center (CRTC) and Washington State University (WSU), looked at Advanced Cross-Laminated Timber (ACLT) made from Western Hemlock, a highly economical and accessible timber species that grows prolifically across the Pacific Northwest.

The 600-square-foot shelter marks the first assembled model of a CLT B-hut, a shelter designed to house troops in temporary and semi-permanent use cases. The closed shelter, which unfolds from a containerized system, offers modular insulation schemes and enhanced life-cycle environmental performance compared with standard B-huts made from plywood and lumber. Its key advantage lies in its ability to be disassembled and relocated with ease.

The seismic test, as seen in the video below from ABC News Channel 20 in Champaign, Illinois, "validated the new types of connectors that the team designed, making sure that occupants inside would be safe during something significant, as we saw, which is equivalent to a 250–500-year event,” said Dr Peter Stynoski, a research civil engineer at the ERDC, in the ABC News interview.

Using an innovative thermal modification process, CRTC created ACLT, which meets the CLT specifications while using Coastal Western Hemlock, a tree species common in the Pacific Northwest, making it much easier and more economical to source the material for U.S. projects.

“Mass timber has a lot of momentum in the Army right now,” said Stynoski. “This project is trying to enable wider sourcing of Class IV materials for more resilient structures in both everyday use and in contested logistics scenarios.”

ERDC’s role in this Congressionally directed research project is to study how ACLT could be used to develop a highly durable, quick-erect building panel system for military housing.

Using its expertise in construction methods, force protection and building technology, ERDC has helped refine concepts and provided rigorous testing at its state-of-the-art facilities, including fragment impact and seismic simulations. This will allow the Department of Defense (DOD) to gauge ACLT’s performance and reliability and ensure it aligns with military requirements.

“One of the ultimate goals is to produce smaller-scale contingency-style structures that can be disassembled, put into a container and moved to another place,” Stynoski said. “Maybe there is a pre-positioned stock of these materials where we might need them in the future. Because of that thermal modification, it is resilient against biological threats. It is extremely dimensionally stable; it doesn’t have issues with moisture expansion and contraction.”

The University of Washington and Washington State University have also supported this effort through advanced modeling.

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Larry Adams | Editor

Larry Adams is a Chicago-based writer and editor who writes about how things get done. A former wire service and community newspaper reporter, Larry is an award-winning writer with more than three decades of experience. In addition to writing about woodworking, he has covered science, metrology, metalworking, industrial design, quality control, imaging, Swiss and micromanufacturing . He was previously a Tabbie Award winner for his coverage of nano-based coatings technology for the automotive industry. Larry volunteers for the historic preservation group, the Kalo Foundation/Ianelli Studios, and the science-based group, Chicago Council on Science and Technology (C2ST).