Abstract
Nails are among the most frequently used fasteners in timber construction, with nail withdrawal capacity (NWC) being a critical performance parameter. Although NWC has been extensively investigated under various conditions, the influence of wood relaxation is often overlooked. This omission can lead to substantial errors in structural design and NWC studies. This study examined the effects of wood relaxation on the NWC of smooth-shank nails. Nails were driven into radiata pine samples conditioned at three moisture contents (MC) and stored under constant conditions for up to 28 days before the NWC test. Results show an exponential decline in the NWC. NWC stabilized two days after driving in wood at 9% MC. In contrast, stabilization required 14 days for wood at 12% and 18% MC. NWC decreased by 40% over 28 days in wood at 9% or 12% MC. However, wood at 18% MC exhibited a 10% increase in NWC during the same period.