Bearing Area Factor

Tabulated compression design values perpendicular to grain Fcl apply to bearings of any length at the ends of the member, and to all bearings 6 in. or more in length at any other location. For bear­ings less than 6 in. and not nearer than 3 in. to the end of a mem­ber, the tabulated design values perpendicular to grain Fc± shall be permitted to be multiplied by the bearing area factor Cb. Values of Cb are given in Table 3.9.

Table 3.8 Temperature Factor (Ct)

Design values

In service moisture content

Ct

T < 100°F

100°F < T < 125°F

125°F < T < 150°F

Ft, E

Wet or dry

1.0

0.9

0.9

Fb, Fv, Fc, and Fcl

Dry

1.0

0.8

0.7

Wet

1.0

0.7

0.5

From National Design Specification for Wood Construction 1991

lb (in.)

0.5

1.0

1.5

2.0

3.0

4.0

6 or more

Cb

1.75

1.38

1.25

1.19

1.13

1.10

1.00

* For round bearing area such as washers, the bearing length lb will be equal to the diameter.

From National Design Specification for Wood Construction 1991