Source: WASHINGTON OFFICE RESEARCH & DEVELOPMENT submitted to
PROPERTIES AND GRADING OF SOLID-SAWN WOOD PRODUCTS
Sponsoring Institution
Forest Service/USDA
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0197030
Grant No.
(N/A)
Project No.
FPL-4714-1
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Mar 11, 2004
Project End Date
Mar 11, 2009
Grant Year
(N/A)
Project Director
Green, D. W.
Recipient Organization
WASHINGTON OFFICE RESEARCH & DEVELOPMENT
1601 N. KENT ST., 4TH FLR, RP-C
ARLINGTON,VA 22209
Performing Department
FOREST PRODUCTS LAB, MADISON LAB HQ - MADISON, WI
Non Technical Summary
We are developing grade and yield information on the properties and yield of structural and non-structural lumber products from small-diameter trees to help expand markets, support small-business and local communities, and show the lumber industry the value of small-diameter trees. More efficient 'mechanical' grading systems will also be established for round logs to be used as structural members to be used in roundwood structures and in guardrail posts systems. Finally, alternatives will be explored for simplification and modernization of the system used to classify lumber property assignments for visually graded dimension lumber.
Animal Health Component
70%
Research Effort Categories
Basic
30%
Applied
70%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
12306502020100%
Goals / Objectives
To promote public safety and support management of the nation's forest resources by developing and applying better grading and property assignment procedures for solid-sawn structural wood products.
Project Methods
Improving the utilization of wood from small-diameter trees and under utilized species is a major challenge for this Problem. The lumber industry in the West has traditionally only focused on trees greater than about 12 inches in diameter, and relatively little information is available on the potential for lumber production from small-diameter trees. The unit will evaluate the yield and properties of lumber from logs cut from small-diameter trees, with emphasis on more efficient 'mechanical' grading systems used for manufacture of trusses, I-joists, and glulam beams. Using small-diameter logs for trusses and columns to construct 'roundwood structures' is another attractive option because processing costs are lower and the economic value may be higher for structurally graded logs. However, current structural grading systems for round beams are overly conservative and may hinder the use of 4- to 6-inch diameter logs in more highly engineered structures. The technical basis will be established for a mechanical grading system for round timbers. Such a system can help establish new opportunities for round timber beams and provide opportunities for small businesses. Finally, the unit will evaluate alternatives for simplifying the system used in the United States for classifying grading requirements for visually graded structural lumber. The current system, unchanged since 1969, is complex, confusing, and not compatible with newer 'stress-class' systems used in Europe and Australia.

Progress 03/11/04 to 03/11/09

Outputs
We studied the various relationships between visual grade requirements and the performance of structural lumber. Data was generated on the relative yields of lumber for various end-use applications. This problem area was terminated as part of a reorganization of work units at the Forest Products Laboratory.

Impacts
A mechanical grading system provides opportunities to increase the market for logs from small-diameter or fire-killed trees over that possible with visual grading. A major engineering consulting firm says the system is essential to the efficient utilization of such logs in highly engineered structures. Documentation of the history of property assignment procedures for wood utility poles will foster rational development of consensus engineering design standards.

Publications

  • No publications reported this period


Progress 10/01/05 to 09/30/06

Outputs
Establishing higher value uses for wood products from small-diameter trees, particularly those growing in over-stocked stands, continues to be a priority in this Problem. Such trees are often targeted for thinning to improve stand health and to reduce the risk of catastrophic wildfire. In the Pacific Northwest and Intermountain regions, Douglas-fir can be a predominant species in such stands. A study of the grade yield and properties of lumber cut from 70- to 90-year old Douglas-fir trees 10-inches and less in diameter found this to be a superior resource for the production of structural lumber. When visually graded 68% of the lumber made Select Structural. This yield is much higher than the 20- to 25% yield for Select Structural lumber found in studies of similar trees grown on commercial plantations in the Pacific Northwest. The highest value product was lumber used in glued-laminated beams. When graded for glulam, 46% made the highest grades used as "tension laminations" for the most critical applications; an additional 22% qualified for the lower glulam grades. Using 4- to 8-inch diameter logs as structural members in engineered roundwood structures is also a current area of research emphasis. Compared to sawing lumber from small-diameter logs, using logs as structural elements has several advantages: processing costs are lower, such logs have a higher economic value, the logs are less susceptible to warp during drying, and the load carrying capacity is higher than the largest rectangular member that could be cut from them. Research has verified, for the first time, property assignments for visually graded logs from small-diameter trees. Although conservative, this verification is important to assure building code acceptance for use in roundwood structures. Research reports submitted for publication have established procedures for the mechanical grading of small-diameter logs. This new approach offers more reliable assignment of allowable properties with properties and grade yields unavailable through visual grading. Wood poles have been used to support utility distribution lines for well over 100 years. In recent years the American National Standard Institute (ANSI) standard for utility poles has taken on added meaning due to changes in definitions and a more rigorous evaluation of property distributions. A paper was developed to review the history and philosophy of the ANSI designated fiber stress to help users more fully understand and appreciate the significance of the changes. A series of crash tests were conducted on round timbers to be used for guard rails. A paper was prepared that summarizes results obtained and their implication for design.

Impacts
A mechanical grading system provides opportunities to increase the market for logs from small-diameter or fire-killed trees over that possible with visual grading. A major engineering consulting firm says the system is essential to the efficient utilization of such logs in highly engineered structures. Documentation of the history of property assignment procedures for wood utility poles will foster rational development of consensus engineering design standards.

Publications

  • Green, D.W. 2005. Grading and properties of hardwood structural lumber. In: Ross, Robert J.; Erickson, John R., eds. Undervalued hardwoods for engineered materials and components. Madison, WI: Forest Products Society: 31-50. Chapter 4.
  • Green, David W.; Gorman, Thomas M.; Evans, James W.; Murphy, Joseph F. 2006. Mechanical grading of round timber beams. Journal of Materials in Civil Engineering ASCE (Jan/Feb): 1-10.
  • Green, David W.; Rosales, Augusto N. 2006. Properties and grading of Danto and Ramon 2x4s. Forest Products Journal 56(4): 19-25.
  • Kretschmann, David; Faller, Ronald; Reid, John; Hascall, Jason; Sicking, Dean; Rohde, John. Small-diameter roundwood, strong-post W-beam guardrail systems. In: Bender, Donald A.; Gromala, David S.; Rosowsky, David V., eds. Proceedings, WTCE 2006-9th world conference on timber engineering; 2006 August 6-10; Portland, OR. Corvallis, OR: Oregon State University. Available on CD. www.wtce2006.com
  • Zerbe, J.K. 2005. Basic properties of undervalued hardwoods. In: Ross, Robert J.; Erickson, John R., eds. Undervalued hardwoods for engineered materials and components. Madison, WI: Forest Products Society: 15-19. Chapter 2.


Progress 10/01/04 to 09/30/05

Outputs
Establishing higher value uses for wood products from small-diameter trees, particularly those growing in over-stocked stands, continues to be a priority in this Problem. Such trees are often targeted for thinning to improve stand health and to reduce the risk of catastrophic wildfire. In the Pacific Northwest and Intermountain regions, Douglas-fir can be a predominant species in such stands. A study of the grade yield and properties of lumber cut from 70- to 90-year old Douglas-fir trees 10 inches and less in diameter found this to be a superior resource for the production of structural lumber. When visually graded, 68% of the lumber made Select Structural. This yield is much higher than the 20- to 25% yield for Select Structural lumber found in studies of similar trees grown on commercial plantations in the Pacific Northwest. Almost 90% of the lumber would make a Machine Stress Rated grade of 2400Fb-2.0E, a common grade used in trusses and I-joists. The highest value product was lumber for use in glued-laminated beams. When graded for glulam, 46% made the highest grades used as "tension laminations" for the most critical applications; an additional 22% qualified for the lower glulam grades. These yields are higher than those generally anticipated by the glulam industry. Using 4- to 8-inch diameter logs are structural members in engineered roundwood structures is also a current area of research emphasis. Compared to sawing lumber from small-diameter logs, using logs as structural elements has several advantages: processing costs are lower, such logs have a higher economic value, the logs are less susceptible to warp during drying, and the load-carrying capacity is higher than the largest rectangular member that could be cut from them. Research has verified, for the first time, property assignments for visually graded logs from small-diameter trees. Although conservative, this verification is important to assure building code acceptance for use in roundwood structures. Research reports submitted for publication has established procedures for the mechanical grading of small-diameter logs. This new approach offers more reliable assignment of allowable properties with properties and grade yields unavailable through visual grading. At the request of a major engineering design firm in Missoula, MT, the new mechanical grading system was used with 6-inch diameter lodgepole pine intended for construction of cable suspension bridges. Wood poles have been used to support utility distribution lines for well over 100 years. Over that time, specifications for a wood utility pole have evolved from the closest available tree more than 15 feet in length to internationally recognized consensus standards that define minimum acceptance to the satisfaction of both producers and users. In recent years the American National Standard Institute (ANSI) standard for utility poles has taken on added meaning due to changes in definitions and a more rigorous evaluation of property distributions. A paper was developed to review the history and philosophy of the ANSI designated fiber stress to help users more fully understand and appreciate the significance of the changes.

Impacts
A mechanical grading system provides opportunities to increase the market for logs from small-diameter or fire-killed trees over that possible with visual grading. A major engineering consulting firm says the system is essential to the efficient utilization of such logs in highly engineered structures. Documentation of the history of property assignment procedures for wood utility poles will foster rational development of consensus engineering design standards.

Publications

  • Larson Debra; Mirth, Richard; Wolfe, Ronald. 2004. Evaluation of small diameter ponderosa pine logs in bending. Forest Products Journal 54(12): 52-58.
  • Wolfe, Ronald W.; Murphy, Joseph F. 2005. Strength of small-diameter round and tapered bending members. Forest Products Journal 55(3): 50-55.
  • Ross, Robert J.; Zerbe, John I.; Wang, Xiping; Green, David W.; Pellerin, Roy, F. 2005. Stress wave nondestructive evaluation of Douglas-fir peeler cores. Forest Products Journal 55(3): 90-94.
  • Green, David W.; Evans, James W.; Murphy Joseph F.; Hatfield, Cherilyn A.; Gorman, Thomas M. 2005. Mechanical grading of 6-inch diameter lodgepole pine logs for the Travelers' Rest and Rattlesnake Creek Bridges. Res. Note FPL-RN-0297. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 17 p.
  • Wolfe, Ronald W.; Kluge, Robert O. 2005. Designated fiber stress for wood poles. Gen. Tech. Rep. FPL-GTR-158. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 39 p.
  • Green, David W.; Lowell, Eini C.; Hernandez, Roland. 2005. Structural lumber from dense stands of small-diameter Douglas-fir trees. Forest Products Journal 55(7/8): 42-50.


Progress 10/01/03 to 09/30/04

Outputs
Approximately 61 million acres of land in the West are at risk from disease, insect attack, and catastrophic wildfire. Small-diameter trees growing in overstocked stands are often targeted for thinning to reduce these risks and improve forest health and biodiversity. Last year's report focused on efforts to document the yield and properties of structural and non-structural lumber from such small-diameter trees; key information to help attract interest in this resource by small and large businesses. This research is continuing. Efforts are now shifting to using logs from small-diameter trees, and trees salvaged from burned areas, as structural members in residential and commercial buildings. Using logs as structural members in building construction is an attractive option because: 1) The processing costs are lower for logs than they would be for sawing and drying lumber, 2) the graded logs often have a much higher value per board foot than the lumber that can be sawn from them, and 3) dry salvaged logs may have little value for other uses. Helping to establish a market for light-frame structures constructed using logs 4- to 7-inches in diameter can help support local communities and keep small-businesses competitive. Research is focusing on three uses for structural logs: logs from fire- and insect-killed trees to be used by the log home industry, small-diameter logs to be used as truss members in roundwood structures, and logs to be used in highway guardrail post systems. Standards already exist for assigning allowable properties to visually graded logs. However, this system is very conservative and not conducive to efficient resource utilization. Working with a large log home manufacturer in the Bitterroot Valley in Montana, a major U.S. grading agency, and the University of Idaho, a 'mechanical' grading system was developed that combines non-destructive testing of each log with visual assessment of defects to more accurately assess properties. The logs tested were all 9 inches in diameter and were from fire-killed trees. Results indicate that, for a required set of properties, the mechanical grading system can produce much higher yields than obtained using visual grading. Commercial adoption of the system by a log home manufacturer will depend upon economic recovery in the industry. Additional research has now shown how to adapt the mechanical grading system for 3- to 7-inch logs. A major engineering firm in Missoula, MT, states that mechanical grading is essential to efficient design of engineered wood structures using small-diameter logs. They have requested assistance in grading lumber for two cable suspension bridges to be constructed from 6-inch diameter, beetle-killed, lodgepole pine. One of these bridges will be constructed over Lolo Creek at Traveler's Rest State Park. Additional research on 5- to 12-inch diameter ponderosa pine indicates little effect of processing, juvenile wood, specific gravity, or stem location on compression strength parallel to the grain. However, dry logs were significantly stronger than green logs.

Impacts
A mechanical grading system has been developed for use with logs from small-diameter trees and logs salvaged from fire-killed trees. It has been shown that the system may significantly increase the yield of logs for a specified set of properties over those available through visual grading. A major engineering consulting firm has stated that the system is essential to the efficient utilization of small-diameter logs in more highly engineered roundwood structures, and is planning to use the system to grade material for two cable suspension bridges constructed with 6-inch diameter lodgepole pine logs cut from beetle-killed trees.

Publications

  • Green, David W.; Gorman, Thomas M.; Evans, James W.; Murphy, Joseph F. 2004. Improved grading system for structural logs for log homes. Forest Products Journal 54(9):52-62.
  • Larson, Debra; Wolfe, Ronald; Mirth, Richard. 2004. Small-diameter ponderosa pine roundwood in compression. In Proceedings, 8th World conference on timber engineering. 2004 June 14-17; Lahti, Finland. Lahti, Finland: RIL Association of Finnish Civil Engineers: 6.
  • Wang, Xiping; Ross, Robert J.; Green, David W.; Brashaw, Brian; Englund, Karl; Wolcott, Michael. 2004. Stress wave sorting of red maple logs for structural quality. Wood Science and Technology 37(6):531-537.
  • Wheeler, Matthew B. June 2004. Strength of visually graded, small-diameter, doweled structural logs. Moscow, UT: University of Idaho. 28 p. M.S. thesis.


Progress 10/01/02 to 09/30/03

Outputs
Approximately 61 million acres of land in the West are at risk from disease, insect attack, and catastrophic wildfire. Small-diameter trees growing in overstocked, dense stands are often targeted for thinning to reduce these risks and improve forest health and biodiversity. Historically, however, trees less than about 16-inches in diameter were seldom used in the West for the production of lumber products. Thus, there is only a small amount of information available on the properties and grade yield of lumber from small-diameter trees, and none of the historical studies included the grade yields for the more advanced grading systems such as Machine Stress Rated (MSR) lumber, extensively used in truss production. Studies are in progress on the grade yield and properties of structural lumber from small-diameter trees for a number of western species to help assess their potential for higher value structural products. Results indicate that the grade yield of structural lumber from small-diameter trees can be just as high as that from larger trees. For example, the yield of No. 2 and better Structural Light Faming from lodgepole pine was 91% (14% of which was Select Structural) and from grand fir the yield of No.2 and better was 89.5 (7% Select Structural). For small-diameter ponderosa pine growing in overstocked stands, the yield of No. 2 and better was only 34%, of which only 3% was Select Structural. When graded as MSR lumber, 83% of the lodgepole pine 2x4's tested would make some MSR grade, and 64% would make a grade of 1650F-1.5E, a popular grade for trusses. With grand fir 2x4's, 66% of the lumber would make an MSR grade, and 62% would make 1650F-1.5E. Virtually none of the ponderosa pine would qualify for MSR lumber. For both lodgepole pine and grand fir, the results indicate a significant premium could be obtained for MSR lumber compared to the price that could be obtained for visually graded structural lumber. A recently completed study indicates even better yields of structural for lumber from small-diameter Douglas-fir trees growing in overstocked stands. In summary, good yields of structural lumber may be obtained from small-diameter trees growing in overstocked stands. However, the yield of high quality lumber will depend upon species, age of the trees, and the conditions of the stands in which the trees are growing.

Impacts
The yield of lumber from small-diameter trees is a function of species, age, and stand conditions. The yield of visually graded structural lumber from small-diameter lodgepole pine and grand fir may be just as good as that from larger trees. Yields were not as good for small-diameter ponderosa pine. A premium may be obtained by producing Machine Stress Rated lumber for use in trusses and I-joists over that which could be obtained through visual grading.

Publications

  • Gorman, Thomas E.; Green, David W. 2002. Characterizing wood properties of small diameter northwest trees. [Abstract]. In: Small diameter timber: Resource management, manufacturing, and markets: Proceedings of a symposium; 2002 February 25-27; Spokane, WA. Pullman, WA. Washington State University: 122.


Progress 10/01/01 to 09/30/02

Outputs
Yellow-cedar is one of the most valuable species in Alaska. A decline and mortality problem is affecting yellow-cedar on more than a half-million acres in southeast Alaska. Because of its high decay resistance, dead snags may remain standing for more than 100 years. Currently, wood from these dead snags is primarily valued for firewood. Mechanical property tests were conducted on 3,433 specimens collected from 108 trees collected near the village of Wrangell in southeast Alaska. The trees were about 900 years old, and the snags had been standing dead from 14 to over 81 years. The results showed that neither strength nor stiffness declined with increasing years since the tree died when compared to wood from live trees. The study also found that "black stain," a discoloration sometimes found in standing yellow-cedar trees, did not affect strength or stiffness of wood from either living or dead trees. It was concluded that wood from dead trees could be graded by current commercial procedures and was suitable for all uses for which wood from live trees might be suitable. Since publication of these results, a number of projects have been initiated in southeast Alaska to improve the utilization of wood from dead cedar. To satisfy the increasing demand for forest products, fast-growing trees such as polar grown on managed plantations are being seriously considered for future supply needs. Available information shows that hybrid poplars have mechanical properties comparable to native species with a similar specific gravity. They are suitable for the production of products such as laminated veneer lumber, laminated strand lumber, and oriented strand board. However, poplars may have their own problems, such as high discoloration potential, difficulty in drying, and high tension wood content. Their fast growth rate and relatively short life span make them ideally suited to cloning so that heritable traits can be impoved more rapidly than trees species than cannot be cloned.

Impacts
Mechanical property tests show that wood from trees that have been standing dead for up to 100 years is just as strong as that from live trees, and thus wood from dead yellow-cedar may be used interchangably with that from live trees. A survey of available information indicates that wood from fast-grown hybrid poplar is suitable for many uses, but that there is a need to use cloning techniques to enhance heritable traits that currently limit applications.

Publications

  • Green, David W.; McDonald, Kent A.; Hennon, Paul E.; J.W. Evans, James W.; Stevens, John H. 2002. Flexural properties of salvaged dead yellow-cedar from southeast Alaska. Forest Products Journal 52(1): 81-86.
  • Green, David. W. 2001. Wood: Strength and stiffness. Encyclopedia of Materials: Science and Technology. Elsevier Science: 9732-9736.
  • Balatinecz, J. J., and Kretschmann, D. E. 2001. Properties and utilization of poplar wood. In: Dickmann, D. I., Isebrands, J. G., Eckenwalder, J. E., Richardson, J., eds. Poplar culture in North America, Part A. Ottawa, Canada: NRC Research Press, National Research Council of Canada: 277-291, Chapter 9.
  • Balatinecz, John J.; Kretschmann, David E.; Leclercq, Andre. 2001. Achievements in the utilization of poplar wood-guideposts for the future. The Forestry Chronicle 77(2): 265-269.