Withdrawal strength of nailed joints with decay degradation of wood and nail corrosion

Abstract

Nailed timber joints are widely used in timber structures, and their deterioration may cause significant damage. We investigated the withdrawal strength of joints using steel wire nails in specimens exposed to a brown-rot fungus. We also examined the effects of nail corrosion on withdrawal strength, because high humidity conditions accelerate not only wood decay but also the corrosion of nails. We found that nail corrosion increased the withdrawal strength. The ratios of withdrawal strength of nailed joints with rusted nails to that of joints with a minimally rusted nails were 1.47 and 1.56 in joints nailed in radial and tangential directions to annual rings, respectively. Withdrawal strength, excluding the effects of nail corrosion, had a negative correlation with mass loss and Pilodyn-pinpenetration-depth-ratio. We estimated the withdrawal strength of the nailed joint with decayed wood and rusted nails by multiplying the values from the empirical formula (obtained from mass loss and Pilodyn-pin-penetrationdepth-ratio) by 1.47 and 1.56 for joints nailed in radial and tangential direction to annual rings, respectively.

Lateral strength of nailed timber connections with decay

“…The connections showed a low load during the initial deformation when there was a small sound region in the boundary between the main and side members, and showed a low load after yielding when the main member had no sound regions. This is because the decay of the main member causes a decrease in the embedding strength and withdrawal resistance [16]. Support for this observation can be understood by the mechanism described above.…”

“…et Curt. ; a brown rot fungus) on a mycelium mat, and the nutrient solution consisted of tap water, including 4% d-glucose, 0.3% peptone, and 1.5% malt extract [7,16]. The main and side members were assembled with paper strings and the lead hole of the main member was aligned with that of the side member.…”

“…There is little research that has examined the effects of decay on the strength of nailed connections with varying connection geometry. When decay is produced throughout main and side members, the strength of nailed connections will decrease because the embedding strength of wood [15] and withdrawal resistance in the main member [16] significantly decreases by decay. However, decay will not necessarily progress in a uniform manner within wood.…”

Stress, Displacement Joints of Gmelina Arborea and Tectona Grandis Wood With Metal Plates, Screws and Nails for Use in Timber Truss Connections

“…The greatest force for truss connections with screws, as occurred in the present study with the greatest displacement in truss connections of G. arborea in the angle of 0° for both tests (Figure 4) and the angle 0° in compression for T. grandis (Figure 4b), is attributed to the greater adherence to wood fibers allowed by the threaded area of the screw, which exerts a greater resistance to extraction during the shear test (Soltis 2010, Moya and. On the other hand, the greatest displacement in truss connections with nails, in G. arborea in angle of 90° for both tests (Figure 4a) and for the angle 90 ° in compression for T. grandis (Figure 4b) can be attributed to the fact that truss connections with nails often subject to lateral forces instead of extraction forces, so lateral forces provide greater resistance to deformation (Takanashi et al 2017).…”

Degradation of shear performance of screwed joints caused by wood decay

“…Information on the remaining strength capacity of joints with decayed wood is required because the strength capacity of joints often affect the structural performance of the construction. Some studies that evaluate the degradation of shear performance of nailed joints caused by wood decay have already been reported [8][9][10].…”