SOUTHERN PINE INSPECTION BUREAU
2002 Grading Rules for Southern Pine Lumber
APPENDIX A -DESIGN VALUES

The single member value for use in fabricated wood structural components may be adjusted in design formulas by modification factors with other design criteria within the designer's judgment.

Tables 1, 3, 6, and 7 show the design values for grades of Southern Pine dimension lumber. Design values for fiber stress in bending, tension, compression parallel-to-grain, and Modulus of Elasticity are derived from test data on full-size structural lumber using procedures specified in ASTM D1990. Design values for horizontal shear and compression perpendicular to grain are derived using procedures specified in ASTM D2555 and ASTM D245.

Tables 4a, 5, and 8a show design values for grades of timbers and decking. Design values are derived using procedures specified in ASTM D2555 and ASTM D245.

Mixed Southern Pine
Southern Pine of the minor species of pond pine and Virginia pine are treated as a separate species group and are so identified on the grade mark. Spruce pine and sand pine are treated as a separate species and are so identified. These species are the only minor species which exist in sufficient volume to find their way into lumber production in certain limited areas, and for which standing timber volume data are published in ASTM D2555.

The characteristics permitted and limiting provisions for grades in the minor species shall be the same as the corresponding grades of the principal species. When the minor species of pond pine and Virginia pine are grade-marked, the mark will indicate the particular species or show "Mixed Southern Pine" and the grades of these species are assigned design values as shown in Tables 6-8a. When spruce pine is grade-marked, the mark will indicate "spruce pine" and sand pine will indicate "sand pine". Design values are assigned according to the procedures on page A15.

Load and Resistance Factor Design Reference Resistance Values
The design values shown in Tables 1a through 8a as well as the design values for MSR and MEL (paragraphs 601 and 604, respectively), Scaffold Plank (paragraphs 500.1, 500.3 and 503.1), and the Decking, Structural, and Industrial lumber covered by SPIB Special Product Rules, are for use with Allowable Stress Design (ASD). Load and Resistance Factor Design (LRFD) is an alternative engineering method. The design values for LRFD, called reference resistance values, can be computed by multiplying the ASD design values by the conversion factors listed in the following table:

CONVERSION FACTORS FOR LRFD USE

Extreme Fiber in Bending "Fb"	Tension Parallel to Grain "F"	Horizontal Shear "Fv"	Compression Perpendicular to Grain	Compression Parallel to Grain "Fc//"	Modulus of Elasticity "E"
2.54	2.70	2.88	2.08	2.40	1.00

These factors have been established in accordance with the procedures set forth in ASTM Standard D5457. The reference resistance values derived using these factors are in units of psi (million psi for "E"). To obtain units of ksi, divide the reference resistance values in psi by 1000.