Pull-up resistance of nailed column-sill joints with steel side plates

Nailed column-sill joints, particularly in braced post and beam constructio ns, are required to have sufficient strength and ductility to resist vertic al forces caused by seismic loading. However, some joint conditions such as insufficient margins and spacing of fasteners reduce them. Strength and du ctility are also affected by diameter, length/diameter ratios of nails and tenon shape. This study was intended to estimate the effects of side margin, nail diamet er and tenon shape on pull-up resistance of nailed column-sill joints with steel plates. ZN65 and ZN90 nails were used and two tenon shapes were prepared. The first tenon was long and large in cross section and the other was short and smal l in cross section. Side margins of the nails from the edges of the sills w ere 4, 8, 12 and 16 times of each nail diameter. The following results were obtained: Nailed column sill joints with large tenons had greater stiff ness than the joints with small tenons. Side margins showed no remarkable effect on stif fness. Increasing side margins changed the major failure mode from sill splitting to withdrawal of nails, which increased maximum pull-up resistance. Joints had the greatest maximum pull-up resistance when side margins were 12 times of the nail diameter. The pull-up resistance was also clearly affected by the number uf interlayers through which shear forces were transmitted from the columns to the sills. The ductility of nailed column-sill joints with large tenons and ZN90 nails was clearly affected by side margins.