Shear Strength of Multi-screw Joints Connected to Decayed Lumber

Abstract

This study aimed to investigate the performance of joints in decayed lumber made with a fastener with multiple connectors. We conducted shear resistance tests of a hold-down connected to Sakhalin fir (Abies sachalinensis) lumber exposed to a brown-rot fungus (Fomitopsis palustris). This hold-down was connected with seven screws. We measured depth of pin penetration with a Pilodyn in the main members after shear tests. We concluded that joint performance when the main member decays is not much reduced for fasteners with multiple connectors when compared to those with a single connector. Depth of pin penetration showed negative correlation with maximum, yield, and ultimate shear resistance. Yield shear resistance of multi-screw joints connected to decayed lumber could be calculated safely by the European Yield Theory.