Unrealistic Design Stresses Proposed for Japanese Species Under JAS 600
As previously reported, new Japanese species groups have been proposed for the first time in a revision committee for JAS600; the Japanese Agricultural Standard for dimension lumber. For this revision, researchers in FFPRI1 conducted in-grade tests for Japanese species and proposed design stresses which are significantly higher than those assigned for currently distributed dimension lumber such as SPF or D Fir(N). COFI Tokyo obtained basic information on the procedures that the FFPRI group followed to calculate these design values. Dr. David Barrett, Professor Emeritus of UBC and an in-grade test authority, examined the output from FFPRI to point out that their calculation lacks the adjustment of the values with “Grade Quality Index (GQI)”, which is the internationally recognized practise designated in ASTM D 1990. COFI then worked with Dr. Barrett in Japan to advise Japanese researchers how the Japanese values should have been properly derived accommodating the GQI. On March 14th, during the annual convention for Japan Wood Research Society in Matsuyama City, Ehime prefecture, Japanese authorities gathered in the city to learn the CQI concept from Dr. Barrett. The participants were from NILIM2, BRI3 and FFPRI. NILIM is in a position to give technical advices to MLIT4, the Ministry that is responsible for assigning the design values. Dr. Barrett’s explanation concluded that the proposed design stresses for Japanese species should have been significantly reduced in cases where the calculations properly followed the standard practise. We are now awaiting their response as to whether they decide to reduce the proposed design stresses for Japanese species.
1) Forestry and Forest Products Research Institute
2) National Institute for Land, Infrastructure Management
3) Building Research Institute
4) Ministry of Land, Infrastructure, Transport and Tourism