“…This may be determined from the CSM 'base curve', which defines the relationship between the maximum strain that a cross-section can endure and its local slenderness, as shown in where ε csm is the maximum attainable strain of the cross-section under the applied loading, ε y =σ 0.2 /E is the yield strain, C 1 is a parameter related to the CSM material model (Figure 3.25) to prevent over-predictions of strength, with a value of 0.1 for austenitic and duplex stainless steels and 0.4 for ferritic stainless steel, ε u =C 3 (1-σ 0.2 /σ u )+C 4 is the predicted strain corresponding to the material ultimate strength, where the values of C 3 are equal to 1 and 0.6 for austenitic and duplex stainless steels (Afshan and Gardner, 2013b) and for ferritic stainless steel (Bock et al, 2015b), respectively, and C 4 is equal to zero for all the stainless steel grades, and c is the local cross-section slenderness, calculated as 0.2 / cr , in which cr is the elastic local buckling stress of the cross-section, and is calculated from Equation (4.11) for a CHS under pure compression or pure bending (Seide and Weingarten, 1961;Reddy and Calladine, 1978;Silvestre, 2007), and thus also combined loading, in which υ is the Poisson's ratio. Note that the CSM base curve for CHS is different to that for RHS described in Chapter 3.…”