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8.10 Member Slendernesses

Table 4.10 displays the slenderness ratios of members. They are significant for the evaluation of the buckling behavior of members subjected to pressure. There is no graphical output option.

Image 8.30 Table 4.10 Member Slendernesses

The member slendernesses are listed by member numbers.


The cross-section's radii of gyration are required to determine the slendernesses.

Length L

The member lengths are indicated in table column B.

Effective Length Factors kcr,y / kcr,z

The effective length factors describe the ratio of buckling length and member length.

Effective length factor:


The buckling length sK refers to the buckling behavior perpendicular to the 'strong' member axis y or the 'weak' member axis z. If no buckling lengths have been defined manually (see Chapter 4.17), the Euler buckling mode 2 is assumed: In this case, the buckling length is equal to the member length. More accurate analyses can be performed with the RF-STABILITY add-on module or in Dlubal's design modules such as RF-STEEL EC3.

Slendernesses λy / λz

The slenderness ratio λ represents a purely geometric value. It is determined from the effective length factor kcr, the member length L, and the radius of gyration i.

λ=kcr Li 

Table columns E and F show the slendernesses that refer to the local member axis system y or z. When asymmetrical cross-sections such as angles are used, two additional columns appear where slendernesses are also shown in relation to the principal axes u and v.