Strength properties of composite laminated wood composed of Z-S treated steel and sugi (Cryptomeria japonica) finger-jointed lumber - Effect of composition upon strength by arranging Z-S treated steel and lamina in compositelaminated wood

Fifteen centimeters wide, 25-cm thick and 6-m long sugi laminated wood (A) and composite laminated wood composed of Z-S treated steel and sugi (B-D) w ere manufactured, and their bending strength properties were evaluated. For composite laminated wood B, Z-S treated steer with 2.3 mm in thickness was placed in tension side, for C and D steer was placed both in compression a nd tension sides. For outermost laminations of composite laminated wood D, low grade lumber with large edge knot size and low MOE were used. All outer most laminations of tension side had a finger-joint at the center. MOE valu es were ranged within five percent of estimated MOEs for C and D, while for B, they were above five percent. Compared with laminated wood A, MOEs of c omposite laminated wood B and C increased by 19% and 56%, respectively. Con sequently, stiffness reinforcement using one piece of steer in tension side seemed less effective than two pieces both in compression and tension side s. Compared with calculate MOEs of C and D based on an assumption that they were not reinforced MOEs of actually composed laminated wood C and D incre ased by 50% and 84%, respectively. These results showed that the reinforcem ent for low grade laminated wood was more effective than that of high quali ty. Proportional limit of composite laminated wood was essentially determin ed by that of Z-S treated steel in tension side. Strain gauge readings take n on the bottom surface at the finger-joint portion were about 0.4% at maxi mum load except composed laminated wood D, and these values were similar to those obtained from tensile test of lumber including finger-joint.