The procedure to solve SI metric is the same as that for customary units. Lumber dimensions are often given in centimeters or millimeters. Stress is in kilopascals (kPa or kN/m2). To convert from allowable stress in Appendix XI from psi (lb/in2) to kPa, multiply Scustomary by 6.8947, Table 24.2.

TABLE 24.2. Metric lumber sizes.

Nominal size (cm)

5.0 x 5.0 7.5 x 5.0 10.0 x 5.0 15.0 x 5.0 10.0 x 10.0 10.0 x 15.0

Actual size (cm)

4.5 x 4.5 7.0 x 4.5 9.0 x 4.5 14.0 x 4.5 9.0 x 9.0 9.0 x 14.0

Problem: What is the maximum point load that can be supported in the middle of a 10 x 15 cm, rough sawed (dimensions are the actual dimensions of the board) simple beam on edge that is 3.0 m long. The board is No. 1 yellow pine?

Solution: Allowable stress from Appendix XI is 1000 lb/in2. Convert this value to SI units kPa

kPa 2

0.00225

kN 3

10.34205 kN-m

3.048 m

Problem: Determine the maximum load that can be supported on the end of a finished 100 mm x 50 mm cantilever beam that is 4.0 m long. The beam is on edge and is No. 2 southern pine.

Solution: Converting allowable stress kN

SSI = 6.8947 —J x SCustomary kN lb = 6.8947 -- x 825 —T

lb/ir2 " in2

solving for K:

2 1m 1m2

100 cm 10,000 cm2

solving for W:

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