DISCUSSION ON RESEARCH ACTIVITY PUBLISHED AS “A PROPOSAL OF ESTIMATION METHOD FOR CRACK INITIATION BY TWO TYPE TESTS A discussion about evaluation method of mode I fracture toughness performance with wood for structural glulam Part 3”

(Wataru KAMBE, Motoaki HIROSUE, Tadao NAKAGOMI, Naoyuki ITAGAKI and Yasuo IIJIMA, J. Struct. Constr. Eng., AIJ, Vol.76, No.666, 1461-1468, Aug., 2011)

Abstract

Experimental achievements on the fracture toughness of wood constituting glulam in the above paper are discussed about the following items: 1) The approach based on fracture mechanics for predicting the fracture strength of wood and wood joint has some serious defects. 2) The description of ductile-like fracture seems inadequate and the J-integral at the maximum load point is doubtful as the fracture toughness for crack initiation, because the tensile softening in the load-displacement curve of wood in 3PB and CT tests is caused by multiple steps of intermittent cracking.