The Structural Performance of the Nail Driven into the Decayed Wood

IRG/WP 19-20652

N Wada, H Isiyama

In late years there are many actions to long-term excellent house realization. We have to consider repair or reinforcement for long-term and safety use of wooden house. There are various studies focused on structural performance of decayed wood. It is important for long-term use of wooden house that structural performance of nailed joint on decayed wood is accurately evaluated. However, there are few studies focused on structural performance of nailed joint on decayed wood. So in this study, structural experiments of the nail driven into decayed wood were conducted, and we tried to make it possible to select a repair method to wooden buildings by quantitatively evaluating the degree of wood deterioration. Brown rot fungus was attached to wood specimens, and they were forcibly decomposed (Decay promotion period: 0, 3, 5, 7, 12, 18 weeks). After the specimen ware air dried, the nails ware driven into them (Figure1) and shear tests were conducted. Confirmation of degree of decay by visual observation ยท Pilodyn was driven into the tested specimen (Figure2), and the degree of decay was quantified. As a result, the following was clarified. Ⅰ. The maximum load decreased as decay advanced. There was a tendency of slip at the displacement of 2 to 6 mm after load rising, the yield point was observed at the displacement of 6 to 10 mm, and finally the nail was pulled out. Also, as the decay progressed, the variation of the maximum load value increased. Ⅱ. The determination coefficient (R2) of the approximate curve showed the relationship between Pilodyn implantation depth and initial stiffness was small. It is difficult to judge the degree of decay with just the Pilodyn implantation depth. It is necessary to consider the moisture content of the wood and the location where the pin is driven.

Keywords: decay, pilodyn, wooden structure, repair, joint, nail

Conference: 19-05-12/16 Quebec City, Canada

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