Original Paper(Vol.61 No.4 pp.347-352)

Proposal of Reinforcing Method Using Wooden Sheets for Reduction of Strength Variation Coefficient of Glued Laminated Timber

Takuro MORI, Koji ADACHI, Kenji UMEMURA, Hidefumi YAMAUCHI and Hiroyuki YANO

Abstract:Glued laminated timber (glulam) composed of mechanical-graded lamina shows higher strength reliability than lumber. However the glulam still has wider strength distribution than steel or concrete for structural applications because of the large difference between the mean and the lower limit value. This study aimed at reduction of the coefficient of variation of the glulam in bending strength by partial reinforcement technique using wooden sheets. The wooden sheets made from bamboo or white oak were covered to several defects on the surface of glulam such as large knots and finger joints. The strength performance and the reinforcement effect for the bending test of the glulam with reinforcement materials were evaluated. As a result, it was clarified that a bamboo sheet (two layers) or a white oak sliced veneer sheet could reinforce the defects, and the average of bending strength was improved due to the improvement in the lower value in the strength distribution.

Key Words:Glulam, Reinforcement, Finger joint, Knot, Bamboo, Carbon fiber