Evaluation of Glued Laminated Timber Made from Low Grade Sugi Laminae

This paper deals with strength properties of non-standard sugi (Cryptomeria japonica D. Don) glulam composed of core low-grade laminae, and face high-grade laminae. In-grade tests were conducted on non-standard glulams, as well as conventional sugi glulams of E65-F225 grade in Japanese Agricultural Standard (JAS). From the results of these tests, non-standard glulams were approximately equal to JAS type glulams both in bending strength and stiffness, which reflect the effectiveness of using high-grade lumber for face laminae. The lower fifth percentile tension strength for non-standard glulams were less than the published standard strength (SS) of E65-F225 grade, though none of the individual strength value less than the SS value. Compression strength for non-standard glulams were lower than for JAS type glulams, however the lower fifth percentile compression strength for non-standard glulams exceeded the SS value of E65-F225 grade extremely