Mechanical Properties

The mechanical properties have been determined using the test procedure described in ASTM designation: D143-52 developed by the American Society for Testing Materials.

Strength group
Four strength groups are used, viz., strength groups A, B, C and D. The earlier grouping method (Burgess, 1958) based solely on compression strength parallel to grain is given in the table below.

			Strength Grouping Table
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Strength Group			Compression strength parallel to grain
						(N/mm2)
	A				greater than 55.2; extremely strong
	B				41.4 - 55.2; very strong
	C				27.6 - 41.4; moderately strong
	D				less than 27.6; weakest
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A refinement to the earlier method took into consideration the basic and grade stresses (Engku Abdul Rahman, 1960). Some timbers have been grouped using this method. For the remaining timbers, the earlier grouping has been used.

Static bending

Data on the Modulus of Elasticity (MOE) and Modulus of Rupture (MOR) have been obtained from published test data (Lee et al, 1979). The mean values are given in the air-dried condition (unless otherwise indicated). If a range is given, it shows the lowest and highest for the timber group.

Compression strength

Data on compression strength perpendicular to grain and compression strength parallel to grain have been obtained from published test data (Lee et al, 1979). If a range is given, it shows the lowest and highest values found for each timber.

Shear strength

Data on shear strength have been obtained from published test data (Lee et al, 1979). If a range is given, it shows the lowest and highest values found for each timber.