Shear Strength of Multi-screw Joints Connected to Decayed Lumber

Takanashi, Ryuya; Toda, Masahiko; Miyauchi, Teruhisa; Mori, Mitsunori; Mori, Takeshi

doi:10.2488/jwrs.64.122

Cited by 3 publications

(5 citation statements)

References 4 publications

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“…However, the difference in K s was not significant at the 5% level, though the mean of K s of the control specimens was higher than that of the decayed specimens. This can be attributed to the large deviation in the values of K s and presumably does not mean that K s will not change even if the member was decayed, as is reported in preceding studies [10,13].…”

Section: Resultsmentioning

confidence: 63%

“…Previously, Takanashi et al conducted a research on the screwed joints with seven screws using the same wood species and screws as this study and reported the effect of decay of the main members on the shear strength [13]. Therefore, in this study, we conducted a comparison between joints with a screw and those with multiple screws regarding the effect of decay.…”

Section: Comparison With the Screwed Joints With Multiple Screws Of Pmentioning

confidence: 91%

“…2. Average yield point of the screws was 1117 N/mm 2 , which was obtained from the bending tests conducted by Takanashi et al [13].…”

Section: Specimensmentioning

confidence: 99%

“…The container in which floras of wood decay fungus and small wood pieces were put on congealed nutrient agar is called "rot fungus feeder unit". Decay tests using rot fungus feeder units have been conducted on nailed joints [8], multiple screwed joints [13], and column-sill joints [15]. This decaying method is suited to decay only a limited part of a wood member.…”

Section: Decay Treatmentmentioning

confidence: 99%

“…Screwed joints are used in combination with reinforcing equipment to reinforce the wooden constructions, however, only a few studies have been conducted [11][12][13], and hence data on the strength degradation of those with decayed wood has been poorly accumulated. Furthermore, the deformation characteristics are unknown.…”

Section: Introductionmentioning

confidence: 99%

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Degradation of shear performance of screwed joints caused by wood decay

et al. 2020

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Shear tests were conducted on screwed joints with decayed main members, and the degradation of shear performance of screwed joints by wood decay was investigated. The differences between decayed and control specimens in yield load (P y), and maximum load (P max) were both significant at the 1% level, while the difference in the initial stiffness (K s) was not significant at the 5% level. The extent of decay was evaluated through Pilodyn penetration depth and the decay depth. Pilodyn penetration depth had no significant relationships with K s , P y , or P max of screwed joints. It is inferred that no significant relationship was found between Pilodyn penetration depth and the strength properties because the range of the measured Pilodyn penetration depth was narrow (16-23.5 mm). The decay depth had a significant inverse correlation with K s of the decayed specimens. There was no significant relationship between the decay depth and P y , or P max. Multiple regression analysis was conducted on K s , P y , and P max using the decay depth and sound wood density (WD h) as 2 explanatory variables. The multiple regression of K s , P y , and P max on the decay depth and WD h were significant at the 1%, 5%, and 1% level, respectively. K s , P y , and P max are inferred to be determined by both the decay depth and WD h. The strength properties of screwed joints with one screw obtained in this study were compared with those of screwed joints with seven screws obtained in a previous study. The difference between K s , P y , and P max of the screwed joints with one screw and those of the screwed joints with seven screws was not significant at the 5% level. It is inferred that shear performance of screw joints with multiple screws are sufficiently estimated from those of screw joints with one screw by simply multiplying the strength properties, even if the main members were decayed.

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Section: Resultsmentioning

confidence: 63%

Section: Comparison With the Screwed Joints With Multiple Screws Of Pmentioning

confidence: 91%

“…2. Average yield point of the screws was 1117 N/mm 2 , which was obtained from the bending tests conducted by Takanashi et al [13].…”

Section: Specimensmentioning

confidence: 99%

Section: Decay Treatmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Degradation of shear performance of screwed joints caused by wood decay

et al. 2020

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Effects of decay on the shear properties of nailed joints parallel and perpendicular to the grain

et al. 2021

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Information on the properties of nailed joints with decayed member is necessary to evaluate the remaining structural properties of timber constructions. In this study, loading tests were conducted on nailed joints parallel and perpendicular to the grain with decayed members, and the relationship between the decrease in shear properties and the loading direction to the grain was investigated. After the loading tests, the extent of decay of the specimens was evaluated by the penetration depth of Pilodyn and the decay depth, and these were compared with the shear properties of the nailed joints. The nailed joints with decay had a low load at the initial deformation, regardless of the loading direction to the grain. The initial stiffness, yield resistance, and maximum resistance of the nailed joints parallel to the grain were negatively correlated with the Pilodyn penetration depth, and those of the nailed joints perpendicular to the grain showed no significant correlation with the Pilodyn penetration depth at the 5% level. The initial stiffness, yield resistance, and maximum resistance of the nailed joints parallel to the grain tended to decrease with increasing decay depth, and those of the nailed joints perpendicular to the grain did not exhibit this tendency. The shear properties of the nailed joints significantly decreased at small decay depths.

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Evaluation method for embedment stiffness of metal washers in bolted timber joints using torque gradient and nut factor

Matsubara,

Teranishi,

Mori

2024

J Wood Sci

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Assessing the residual performance of timber joints affected by decay is important for seismic diagnosis and reinforcement of timber structures. This study introduces a method to evaluate the embedment stiffness of metal washers in bolted timber joints using a torque wrench. Formulas for the embedment stiffness of metal washers using the torque gradient (the gradient of the tightening torque against the tightening rotation angle of the nut) and the nut factor are presented and the calculated values are compared with experimental values obtained by conducting tightening tests with a torque wrench and embedment tests of metal washers in bolted joints made from Japanese cedar, Hiba, and Japanese cypress. The results show that the experimental values of the embedment stiffness of metal washers in Japanese cedar and Hiba are generally within the range of the values calculated from the minimum and maximum values of the nut factor. However, for Japanese cypress, the values calculated from the maximum value of the nut factor exceed the experimental values. This was presumably due to locally large frictional forces generated on the bearing surface or threaded part.

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Shear Strength of Multi-screw Joints Connected to Decayed Lumber

Cited by 3 publications

References 4 publications

Degradation of shear performance of screwed joints caused by wood decay

Degradation of shear performance of screwed joints caused by wood decay

Effects of decay on the shear properties of nailed joints parallel and perpendicular to the grain

Evaluation method for embedment stiffness of metal washers in bolted timber joints using torque gradient and nut factor

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