Evaluating the difference of shear strength in stress direction of glued-laminated timber

In Japan, referenced shear strength of glued-laminated timber is specified in MLIT (Ministry of Land, Infrastructure, Transport and Tourism) Notification No. 1024 in 2001, and there is a difference of strength depending on the direction of stress acting on the material. According to the current Japanese building code, the shear strength in the width direction is set to a small value of 0.78 to 0.88 times to that in the lamination direction. However, there is no technical basis at the time when the standard was established, so early verification and improvement are demanded from researchers and engineers of wooden structure. In this research, three-point bending test, full-scale block shear test and JIS (Japanese Industrial Standard) block shear test on glued-laminated timber were conducted. The glued-laminated timber was made of Japanese cedar, Japanese cypress, Scots pine and Douglas fir. Comparing the average value of the shear strength obtained by each test method, it was found that the shear strength in the width direction has the same or higher value than the lamination direction, and there is no tendency like the current building code. Comparing each test method, it was found that different characteristic values were obtained due to influence of size effect and notch effect.