New timber column design equations - new formulations and modulus of elasticity values

Abstract

Recent bending and compression tests on currently produced SA pine and low-density Eucalyptus saligna have shown that the fifth percentile modulus of elasticity, MOE, is lower than the values published in SASS 0763 (7994). These tests have shown that the fifth percentile values should be used when calculating the stability of timber columns and beams. Current editions of SASS 0763 (7994), however, use the mean modulus of elasticity to calculate column strengths. The author presents data and graphs to support his findings and proposes new sets of equations for column strength that look similar to the steel design code equations found in SABS 0 7 62- 7 ( 7 993). He also suggests reduced fifth percentile modulus of elasticity values to be used for the calculation of compression member strength. Graphs are presented that show the good fit of the new proposed equations with the current accepted equations.