Sg. Winistorfer, PRACTICAL CONSIDERATIONS OF DOWEL BEARING STRENGTH AND ANNULAR RING FASTENER ORIENTATION, Forest products journal, 45(7-8), 1995, pp. 64-68
The orientation of the fastener with respect to annular growth rings c
an affect the strength of laterally loaded wood connections. Connectio
n properties are dependent on localized dowel bearing strength, which
in turn is dependent on the specific gravity of the earlywood and late
wood that constitute the annular rings. In the study reported here, do
wel bearing strength was determined for matched specimens of three sof
twood species (southern pine, Douglas-fir/larch, and spruce-pine-fir)
using a 0.131-inch-(3.33-mm-) diameter nail. Tests were conducted with
the nail oriented radially and tangentially with respect to the annul
ar rings. Specific gravity, percentage of latewood, and number of ring
s per inch were also determined for each specimen. Results illustrated
that although the difference between radially and tangentially loaded
dowel bearing strength can be significant, this difference is of no p
ractical consequence. The combination of fastener size (in contact wit
h many growth rings) and the relatively infrequent occurrence of very
coarse- and flat-grained lumber resulted in nearly equal values of dow
el bearing strength in the radial and tangential directions. Little co
rrelation was found between dowel bearing strength and percentage of l
atewood or number of rings per inch.