The calculation of geometrical constants for irregular cross-sections of rods and beams

Extruded rods and beams may have cross-sections with very complicated shapes; as a consequence, cross-sectional properties relating to stiffness, strength and stability cannot be calculated analytically, nor can they be obtained from a handbook or the manufacturer. For research purposes a special program was written in order to calculate geometric properties such as the torsion constant, the warping constant and the shear centre location; it made use of an advanced mesh generator and was run on a large computer. The need of a medium size company, that only possessed an 8-bit microcomputer led to a simplification of the program. An investigation of the mechanical (torsional) behaviour of the members led to the choice of an element and a strategy for mesh-division such that calculation of the geometrical constants could be done simply on the microcomputer. The calculations could be confirmed by comparison with more elaborate calculations