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1.
Optimizing the manufacturing conditions of veneer strand-flanged I-beams was continued in this study and focused on the strand
density and preparation method. Three levels of strand density were used, while the strands were prepared by either saw or
roll-press splitter. The main results indicated that: within the compaction ratios (1.4–2.3) investigated in this study, the
strand with lower density showed slight improvement in the dimensional stability and the bond strength between web and flange,
but not in bending properties of the I-beams. The strand preparation method was concluded to be dependent on species for akamatsu,
sugi, and bamboo strands; roll-press splitter-prepared strands tended to negatively affect dimensional stability and mechanical
properties of the I-beams. When using akamatsu or sugi strands, low density allowed the possibility of using lower resin application
rates between strands.
Part of this paper was presented at the 54th Annual Meeting of the Japan Wood Research Society in Sapporo, August 2004 相似文献
2.
The balance of strength between the flange and web parts of veneer strand flanged I-beam was investigated by the following
methods: (1) use of different web material types, such as plywood, oriented strand board (OSB), particleboard (PB), and medium
density fiberboard (MDF), that have different strength properties; and (2) fabrication of I-beams with low-density flanges
using low-density strands with PB web material. Replacing PB or MDF with plywood showed slight significant improvement in
the modulus of rupture but not in the modulus of elasticity of the entire I-beam. However, PB and MDF showed competent performance
in comparison with OSB, thus strengthening the promising future of the use of PB or MDF as web material to fabricate I-beams.
Hot-pressing conditions used for I-beam production exerted slightly adverse effects on the bending properties of PB, but not
on MDF, OSB, and plywood web materials. The flange density of 0.60 g/cm3 was considered to be the lower limit that provides I-beams with balanced mechanical properties and dimensional stability. 相似文献
3.
Optimization of the manufacturing conditions of the veneer strand flanged I-beam invented in the previous study was investigated using different combinations of strand dimensions, resin types between web and flange, different pressing times, and different wood–resin moisture contents under conventional hot pressing conditions. The main results revealed that the strand dimensions have no effect on the bending properties of the flange part and the dimensional stability of the I-beam. Increasing the resin application rate between strands was found to improve the dimensional stability of the I-beams. The use of isocyanate (MDI) resin between web and flange significantly improved the bond strength between web and flange, the modulus of rupture of the I-beam, and the modulus of rupture of the flange part. Dimensional stability was also improved. Shortening the pressing time from 20 to 12min was found to be feasible. Using low wood-resin moisture content was found to interfere with the curing of the phenol–formaldehyde (PF) resin at the flange part resulting in poor quality beams. Of the three moisture content levels tested, 12% was found to be the optimal level for producing I-beams with balanced mechanical properties and dimensional stability.Part of this work was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, March 2003 相似文献