Truss Design Module HelpSteel design criteria for AS 4600 Steel design criteria for AS 4600 Axial tension NSF An. kt Axial compression CFT Restraint L33 L22 L Torsion K33 K22 K Torsion Bending Cb33 Cb22 CLT restraint User R. Shear Loc. Shear. a (Stiffeners) Combined forces Cm33 Cm22 Braced minor (Frame type 2) Braced major (Frame type 3) Web crippling Bear. L. Load. Cond. Fl. Sup. Cond. Distortional buckling Braced Buck. Lm. NSFSets the net reduction factor (NSF) applied to the gross section area to obtain the net section area. If both NSF and a direct net area (An) are provided, the NSF value takes precedence and is used to calculate the net area.