2013 Volume 59 Issue 4 Pages 179-187
To study the influence of whorled knots on the bending strength of Japanese red pine (Pinus densiflora) two-side-surfaced beams, static bending tests were conducted for each visual grade specified by the Japanese Agricultural Standard for lumber. Rectangular beams were also tested for comparison. The influence of whorled knots on bending strength was less for two-side-surfaced beams than rectangular beams, and the maximum load of two-side-surfaced beams was significantly higher than that of rectangular beams of low visual grade. Based on the experimental data, the estimated maximum load ratios of two-side-surfaced beams to rectangular beams were 1.59, 1.62, and 1.95 for visual grade I, II, and III, respectively, when both beams were sawn from 300mm-diameter logs. It was shown that the two-side-surfaced beams had more advantages than rectangular ones in regard to efficient use of logs with identical diameter.
