Journal of the Korean Wood Science and Technology

The Korean Society of Wood Science & Technology (한국목재공학회)
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Evaluation of Allowable Bending Stress of Dimension Lumber; Confidence Levels and Size-adjustment

  • Pang, Sung-Jun (Department of Forest Sciences, College of Agriculture & Life Sciences, Seoul National University) ;
  • Lee, Jun-Jae (Department of Forest Sciences, Research Institute for Agriculture and Life Sciences, College of Agriculture & Life Sciences, Seoul National University) ;
  • Oh, Jung-Kwon (Department of Forest Sciences, Research Institute for Agriculture and Life Sciences, College of Agriculture & Life Sciences, Seoul National University)
  • Received : 2013.06.13
  • Accepted : 2013.09.17
  • Published : 2013.09.25
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Abstract

The aim of this study was to investigate the processes for evaluating the allowable bending stress. The confidence levels and the size-adjustment in standards were reviewed with experimental data. The results show that, (1) KS F 2152 was more strict than others overseas standards due to the higher confidence level. The 5% NTL of bending strengths by a method in KS F 2152 were lower than the overseas standards and more specimens were required for evaluating the structural properties according to KS F 2152. (2) Due to the absence of size-adjustment method in domestic standards, the specified size and the exponential parameters on the size-adjustment equation were reviewed by size factors. The specified size (width: 286 mm, length: 6096 mm), and the exponential parameters (w: 0.29, l: 0.14) will be suitable for developing the allowable bending stress in domestic standard. (3) The size adjusted allowable bending stresses of No. 2 grade Korean pine were lower than the allowable stresses tabulated in KBC even though less strict method (75% confidence level) to calculate 5% value was used. The allowable stresses tabulated in KBC are needed to be reviewed by continuous experimental data.

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References

  1. American Forest & Paper Association. 2011. National Design Specification (NDS) for Wood Construction Supplement: Design Values for Wood Construction 2012 Edition.
  2. AS/NZS 4063. 2. 2010. Characterization of structural timber part 2: determination of characteristic values.
  3. ASTM D1990. 2007. Standard practice for establishing allowable properties for visually-graded dimension lumber from in-grade tests of full-size specimens.
  4. ASTM D2915. 2010. Standard practice for sampling and data-analysis for structural wood and wood-based products.
  5. Barrett, J. D. and W. Lau. 1994. Canadian lumber properties. Canadian Wood Council.
  6. Barrett, J. D., F. Lam, and W. Lau, 1995. Size effects in visually graded softwood structural lumber. Journal of materials in civil engineering 7(1): 19-30. https://doi.org/10.1061/(ASCE)0899-1561(1995)7:1(19)
  7. CSAO86-09. 2009. Engineering Design in Wood. Canadian Standards Association, Mississauga, Ontario, Canada.
  8. Evans, J. W., D. E. Kretschmann, V. L. Herian, and D. W. Green. 2001. Procedures for developing allowable properties for a single species under ASTM D1990 and computer programs useful for the calculations. US Department of Agriculture, Forest Service, Forest Products Laboratory.
  9. ISO 13910. 2005. Structural timber - characteristic values of strength-graded timber - sampling, full-size testing and evaluation.
  10. Korean Building Code. 2009. Minister of Land, Transport and Maritime Affairs notification 2009-1245.
  11. KS F 2152. 2004. Establishing allowable properties of softwood structural lumber.
  12. KFRI notification 2009-1. 2009. Softwood structural lumber. Korea Forest Research Institute.
  13. Lee, J. J., G. C. Kim, K. M. Kim, and J. K. Oh. 2003. Distribution Characteristics of Bending Properties for Visual Graded Lumber of Japanese Larch. MokchaeKonghak 31(5): 72-79.
  14. Lim, J. A., J. K. Oh, H. M. Yeo, and J. J. Lee. 2010. Feasibility of Domestic Yellow Poplar (Liriodendron tulipifera) Dimension Lumber for Structural Uses, MokchaeKonghak 38(6): 470-479. https://doi.org/10.5658/WOOD.2010.38.6.470
  15. Oh, S. C., M. J. Park, and K. Shim. 1993. Stress Grading of Domestic Softwood $2{\times}4$ Lumber. Journal of Korea Furniture Society 4(1): 8-13.
  16. Pang, S. J., J. K. Oh, C. Y. Park, J. S. Park, M. J. Park, and J. J. Lee. 2011. Characteristics Evaluation of Bending Strength Distributions on Revised Korean Visual Grading Rule, Mokchae Konghak 39(1): 1-6.
  17. Pang, S. J., J. S. Park, K. H. Hwang, G. Y. Jeong, M. J. Park, and J. J. Lee, 2011. Bending strength of Korean softwood species for $120{\times}180$ mm structural members, J. Korean Wood Sci. & Tech. 39(5): 444-450. https://doi.org/10.5658/WOOD.2011.39.5.444
  18. Park, C. Y., S. J. Pang, J. S. Park, K. M. Kim, M. J. Park, and J. J. Lee. 2010. Study of the distribution properties and LRFD code conversion in Japanese larch. MokchaeKonghak 38(2): 94-100. https://doi.org/10.5658/WOOD.2010.38.2.94

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