SBIR-STTR Award

Structural Testing of Branched Timber and Truss Assemblies
Award last edited on: 1/26/2016

Sponsored Program
SBIR
Awarding Agency
USDA
Total Award Amount
$461,189
Award Phase
2
Solicitation Topic Code
8.1
Principal Investigator
Roald Gundersen

Company Information

Whole Trees Inc (AKA: Whole Trees LLC~Essentium Materials LLC)

East 2890 Lorenz Road
Stoddard, WI 54658
   (608) 452-3894
   info@wholetrees.com
   www.wholetrees.com
Location: Single
Congr. District: 03
County: Vernon

Phase I

Contract Number: ----------
Start Date: ----    Completed: ----
Phase I year
2011
Phase I Amount
$99,689
USDA secretary, Tom Vilsack recently urged the Forest Service to "develop new markets" for forest by-products, which encourage healthy timber management. Small-diameter round timber is an abundant by-product of healthy timber management and could serve emerging green commercial markets if technical barriers, specifically round timber "connections", can be solved. Whole Trees Architecture and Construction (WT), a leader in round timber design and construction, has identified that no testing has been performed on the moment resisting connection of a natural tree branch (branching timber). WT anticipates proof that the branching connection is stronger than any man-made connection. WT uses branching timbers to develop axial and lateral load resisting structures, in-part solving the "connection" problem. WT commercial and institutional clients are interested in its application and market analysis suggests that the national green building industry is poised for such a construction material. For over 17 years, Project Director, Roald Gundersen, AIA has demonstrated the structural integrity of small diameter round timber and branching timbers in building projects of many scales including a university classroom building. However, lack of critical structural design guidelines based on scientific testing is a continuing barrier to future commercialization. To better understand and promote this material, WT has engaged in partnership with the USDA Forest Products Laboratory to document and verify the strength and structural characteristics of small-diameter branching timbers. This testing and model information will be the foundation for the development of an Evaluation Report from the International Code Council- Evaluation Service (ICC-ES). Anticipated technical results of branched timber research include: Expanded understanding by code officials, contractors, architects and foresters of round timber integration in a wide range of construction applications; Improved structural integrity, safety and durability of round timber frame construction; Substitution of round timber frame for steel and concrete in infrastructure; Increased carbon sequestration of timber frame structures; Reduced embodied energy, and hence cost and pollution, in construction processes. Anticipated economic results of this project include: Increased value-added products from forest residue; More forestry and round timber-framing jobs, and rural economic development; Increased incentives to perform timber stand improvement and timber values; Increased competitiveness of timber-framing into commercial and institutional infrastructure markets, and reduced imports of lumber, steel, and concrete. Anticipated social and environmental results of this project include: More construction dollars recycling back into local communities; Reduced need for government subsidies for timber stand improvement and rural economic development; Reduced wildfire threat and disease pressures from thinned forest stands; and improved health, diversity and CO2 sequestration of forests.

Phase II

Contract Number: ----------
Start Date: ----    Completed: ----
Phase II year
2012
Phase II Amount
$361,500
USDA secretary, Tom Vilsack, has urged the Forest to prioritize "protecting and maintaining all American Forests, including state and private lands. ... The Forest Service must play a significant role in the development of new markets and ensure their integrity." Small-diameter round timber is a vast and under-used waste product of well-managed forests. At the same time, the structural building systems market is currently dominated by steel and concrete structural systems. Round timber can substitute for steel and concrete in medium and large scale construction under Type IV: "Heavy Timber Framing." Round timber can qualify for up to eight US Green Building Council Leadership in Energy and Environmental Design (LEED) credits, more than triple any other "green" structural material and almost a third of the credits necessary to achieve LEED Silver rating, now the standard for new federal buildings. This convergence of factors will benefit WT's efforts to build an industry. Research conducted at the FPL indicates the superior strength of round wood timbers. Small-diameter round timbers are 50% stronger in bending than an equivalent square section of milled timber. WHOLETREES ARCHITECTURE AND STRUCTURES (WT), a leader in round timber design and construction, has conducted Phase I research into the strength of the branched connection between tree limbs and trunk. Structural tests, conducted at the Forest Products Laboratory in Madison, WI, applied lateral or axial force to a variety of branching Ash tree specimens and found the strength of the branched connection to be significant. Phase I testing demonstrated that out-of-plane bending of tributary branches or stem is critical to overall timber load capacity. Optical metrics of branched timbers along with structural analysis can be effective predictors of load capacities. A combination of slenderness ratio, branched geometry, and out-of-plane curvature seem to be a strong estimator of the load capacities. WT will, in Phase II, conduct focused testing to refine the selection criteria for specimens - a combination of slenderness ratio, branched angle and out-of-plane curvature - and develop the best visual parameters for selection. These selection criteria will be used for in-field sorting, and to develop proprietary grading software. Designing and testing original connection subassemblies will be crucial to bringing the strength of the branched timber to market. WT will build successful connection designs into full-scale branched column-truss assemblies.