Robert Ross & Shayne Martin – USDA Forest ServiceForest Products Laboratory
A year ago, the Forest Products Laboratory staff received a unique request.
That request came through a relationship built on cooperative research between the Department of Defense and the U.S. Department of Agriculture Forest Service, Forest Products Laboratory (FPL). This connection resulted in an amazing story of a 3,000-lb stack of legacy mahogany and other vintage lumber of incalculable value being used in the restoration of many historical wood objects at the U.S. Capitol building.
While our country reflects on the attack of January 6, 2021, which resulted in the damage or destruction of many treasured historical artifacts, we also reflect on the story of the wood used to repair what was thought to be irreplaceable. That story shone as a bright light and sign of hope in an otherwise dark situation.
On Wednesday, January 6, 2021, the U.S. Capitol building was the target of an attack that left it ransacked and vandalized. The destruction of many irreplaceable historical wooden artifacts and objects, including doors, intricate millwork, moldings, desks, and podiums, was extensive.
New video footage has been released of blast testing performed on cross laminated timber (CLT) structures, and it’s quite a sight to see.
The Forest Products Laboratory, in cooperation with WoodWorks and the Softwood Lumber Board, led a second round of live blast testing in 2017 at Tyndall Air Force Base in Panama City, Florida.
The charges in the videos were large enough to potentially cause lethal injury, and the structures survived. The objective of these studies was to demonstrate the capability of CLT structures to resist airblast loads, thereby allowing the military to incorporate mass timber materials like CLT into their construction projects.
The following is an update to a previous LabNotes post. The updated version was recently featured on the USDA and Forest Service blogs:
All three structures remained standing after the testing – even tests designed to take the structures well beyond their design intent. (Photo courtesy of Air Force Civil Engineering Center AFCEC, Tyndall Air Force Base)
At the USDA Forest Service’s Forest Products Laboratory (FPL), researchers sometimes get a little destructive. They bend and break wood samples of all sizes, and even shoot lumber out of a cannon at 100 miles per hour.
But explosions? That’s a bit out of their wheelhouse. Not that wood can’t handle it. Particularly when it’s used in engineered products like cross-laminated timber, or CLT, which FPL researchers have studied from many angles, including fire performance, use in earthquake-prone regions, and the effects of moisture on CLT. Made of alternating layers of dried lumber boards stacked at 90-degree angles, CLT is exceptionally strong and stable and can be used as walls, roofs, and floors in mid-rise buildings. Continue reading →
Recent tests of CLT structures show just how tough this material can be. A series of live blast tests were conducted at Tyndall Air Force Base by WoodWorks in cooperation with the U.S. Forest Service and Softwood Lumber Board.
The specifics of the tests are outlined in this great Woodworking Network article, but if you’re looking for a spoiler, the results were promising, and they “will be used to further expand the use of wood solutions for Department of Defense applications and other blast-resistant construction.”
You can view all the tests at http://bit.ly/2hwVE1g and we posted our favorite below. While not a dramatic view of the explosion itself, this high-speed shot shows the wood panels moving with the force of the blast without being destroyed.
WoodWorks will publish the complete results in 2017.