SBIR-STTR Award

This project is the last piece of the round timber production puzzle for WholeTrees Structures' SBIR-funded research initiatives: improved selection and grading procedures for round pole timber, building on ASTM visual grading rules for poles and piles, but for structural spanning applications. This research project is based on a solid body of prior work (Wood et al. 1965; Goodman et al. 1981; Wang et al. 2001) correlating in-field nondestructive valuation (NDE) with tested bending strengths and the modulus of elasticity (MOE). WT proposes to refine and implement a cost-effective selection and grading methodology for commercial production. USDA secretary, Tom Vilsack, has urged the Forest Service to "develop new markets" for forest by-products that encourage healthy timber management. WholeTrees® Architecture & Structures (WT) has successfully commercialized a line of round timber structural systems for the non-residential construction industry. The company is creating value from the abundant cullings of well-managed forests with ongoing structural testing of branching round timbers, and subassembly connection tests (2012 Phase II SBIR); development of a software-based grading system for branched round timber, (SBIR Phase I 2013), and perhaps most importantly, successful entry into commercial markets. This research project will optimize the selection and grading of round timber used for spanning to reduce costs and improve product safety, performance and reliability. This research project will: 1) build on previously demonstrated effective Non-Destructive Evaluation (NDE) techniques; 2) further correlate NDE with destructive testing; and 3) develop a cost-effective set of grading procedures for manufacturing as Phase I proof of concept. OBJECTIVES: This project will allow WholeTrees to optimize the selection and grading of round timber used for spanning to reduce costs and improve product safety, performance and reliability. This research project will: 1) build on previously demonstrated effective Non-Destructive Evaluation (NDE) techniques; 2) further correlate NDE with destructive testing; and 3) develop a cost-effective set of grading procedures for manufacturing as Phase I proof of concept. Current state, round timbers rely on ASTM grading standards developed for utility poles and piles and not for spanning members in bending. Relying on default standards for milled timbers substantially reduces grades to a Co-efficient of Variability (COV) of 25% to 30% verses those found for poles of 10% to 15%.The goal of this proposed research is to establish a relationship between a rapidly-tested Modulus of Elasticity (MOE) value and the calculated design load of a round timber structural member. Pairing this relationship with efficient NDE methods for harvest or manufacturing facilities is necessary to support the development of this product from a custom engineered solution to one which can be provided at scale to meet a growing demand for structural round timber. Phase I Technical Objectives Are To: 1) Develop a cost-effective NDE screening process for red pine using existing NDE techniques to assess the stiffness of 100 timbers. 2) Work with the USDA FPL to destructively test these timbers and determine their bending strength. 3) Establish a reliable correlation between tested stiffness (MOE) of timbers and their tested strength in bending and compression. 4) Record time and material costs of draft procedures and perform cost-benefit analysis to determine scaling feasibility.

Former USDA secretary, Tom Vilsack, has urged the Forest Service to "develop new markets" for forest by-products that encourage healthy timber management WholeTrees® Architecture and Structures, LLC (WT) creates value from an abundant, near-waste byproduct of well-managed forests: small-diameter round timber (SDRT). WT uses debarked, un-milled whole timbers and proprietary steel connections as a cost-competitive and environmentally sound structural building material for columns, beams, and truss assemblies in place of steel, concrete or milled lumber. WT will continue to optimize the selection and grading of round timber used for spanning to reduce costs and improve product safety, performance and reliability. This research project will: 1) test Phase I established machine grading (MG) procedure on two softwood species; 2) further correlate MG procedure with destructive testing; and 3) value-engineer truss assemblies based on optimized design values. The goal of this proposed research is to establish the relationship between a rapidly-tested Modulus of Elasticity (MOE) value and the calculated design load of an SDRT structural member. This proposed SBIR Phase II project will allow WT to further develop and integrate standardized selection, grading, and manufacturing procedures for structural SDRT. The findings will lead to an expanded supply chain, improved design values, and associated cost reductions as well as improved product safety, performance, and reliability. These developments will open pathways to advanced rural manufacturing of bio-based building products. An improved market for small-diameter round timber will increase economic opportunity for rural communities while protecting America's forest resources.