Structural Testing of Round Branched Timbers

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.