Steel member design: Utilisation ratios

Measures of the utilisation of the member’s capacity. Remember that their values will not be directly comparable from design code to design code, and that the calculation of some of them is highly non-linear. If any of them is greater than 1, then the member has failed.

All of the utilisations are the worst of their kind encountered along the member’s length.

Envelopes of utilisation ratios are the maximum and minimum of the utilisation ratios calculated for each permutation in the envelope.

The ratios available are:

Ratio	Comment
Overall	worst of all the other utilisation ratios
Local Combined	local force/capacity interaction
Local Axial
Local Moment Major	local major axis moment
Local Moment Minor	local minor axis moment
Local Shear Major
Local Shear Minor
Local Torsion
Buckling Combined	buckling interaction
Buckling LT	lateral torsional buckling
Buckling Axial Major
Buckling Axial Minor