The US Army has 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-in-250-year earthquake.

The testing by the US Army Engineer Research and Development Center’s (ERDC) construction engineering research laboratory, in collaboration with the Composite Recycling Technology Center (CRTC) and Washington State University, looked at advanced cross-laminated timber made from Western Hemlock, a highly economical and accessible timber species that grows prolifically across the Pacific Northw-West.

The seismic test “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 Peter Stynoski, a research civil engineer at the ERDC.

Innovative materials

Using an innovative thermal modification process, CRTC created advanced CLT, which meets the CLT specifications while using coastal Western Hemlock, making it much easier and more economical to source the material for US 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 Congress-directed research project is to study how advanced CLT 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 Defence to gauge advanced CLT’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 the thermal modification, it is resilient against biological threats; it is extremely dimensionally stable; it doesn’t have issues with moisture expansion and contraction, he added.

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

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