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

Rintaro Ueda,Kei Sawata,Takanobu Sasaki,Yoshihisa Sasaki

doi:10.1186/s10086-021-02006-1

Abstract

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.

Highlights

In recent years, the lifespans of timber constructions have increased as the use of timber in construction could help us meet the global sustainable development goals (SDGs)
The deformation of the nails can be classified into two modes, as shown in Fig. 8: the mode that has a plastic hinge in the nail and the mode with two plastic hinges
Shear tests were conducted on nailed joints parallel and perpendicular to the grain with a decayed main member, and the degradation of the shear properties of the nailed joints due to decay was investigated

Summary

Introduction

The lifespans of timber constructions have increased as the use of timber in construction could help us meet the global sustainable development goals (SDGs). The integrity of wood can be compromised by wood– rot fungus and termites. These significantly degrade the mechanical properties of wood, and the degradation may result in a decrease in the load-bearing capacity of timber construction [1]. The effects of decay on the initial stiffness, yield resistance, and maximum resistance of timber joints were clarified in these studies. These were obtained from shear tests of timber joints parallel to the grain; few studies have been conducted on timber joints perpendicular to the grain

Methods

Results

Conclusion