The register Members | Stability is available if the 'Perform stability analysis' check box is selected in the Members | Basis register. Here, you can make further settings for the stability analyses.
The 'Design parameters' are divided into several categories that differ depending on the design standard. The following sections describe the parameters of these standards:
EN 1995
Stiffness reduction
This category is relevant for the time-dependent behavior of compression members with large permanent load components: According to the German National Annex NCI NA.5.9, the influence of creep must be considered for compression members in service classes 2 and 3 if the design value of the permanent and quasi-permanent load component exceeds 70 % of the design value of the total load. This consideration may be achieved by reducing the stiffness by the factor 1/(1 + kdef).
Load application point
In the Effective Lengths dialog box, you can specify how the ideal elastic critical moment Mcr is determined. With the Eigenvalue method, the load application point can significantly influence the critical moment for lateral-torsional buckling: A load acting on the top flange of a bending beam in the direction of the shear center has a destabilizing effect. If, on the other hand, the load pulls on the bottom flange, it has a stabilizing effect. Use the selection fields to define the 'Vertical position'.
For members with a constant cross-section, the load application point also influences the definition of the equivalent member lengths according to the footnote in [1] Table 6.1.
Settings for eigenvalue method
The 'Activate warping stiffness' check box is relevant if the ideal elastic critical moment Mcr is determined using the eigenvalue method. This allows you to control whether the warping resistance Iω is to be considered for lateral-torsional buckling. The warping stiffness is not relevant in the standard.
NDS
Representative cross-section dimension for tapered compression members according to 3.7.2
In this category, you can specify which equation should be used to determine the representative cross-section dimension of tapered compression members:
- Eq. 3.7-2: for specific standard support conditions
- Eq. 3.7-3: for all other support conditions
Load application point of positive transverse loads
In the Effective Lengths dialog box, you can specify how the ideal elastic critical moment Mcr is determined. With the Eigenvalue method, the load application point can significantly influence the critical moment for lateral-torsional buckling: A load acting on the top flange of a bending beam in the direction of the shear center has a destabilizing effect. If, on the other hand, the load pulls on the bottom flange, it has a stabilizing effect. Use the selection fields to define the 'Vertical position'.
Settings for eigenvalue method
The 'Activate warping stiffness' check box is relevant if the ideal elastic critical moment Mcr is determined using the eigenvalue method. You can use it to control whether the warping resistance Iω should be considered in the lateral-torsional buckling analysis. The warping stiffness is not considered in the standard.
CSA O86
Load application point of positive transverse loads
In the Effective Lengths dialog box, you can specify how the ideal elastic critical moment Mcr is determined. With the Eigenvalue method, the load application point can significantly influence the critical moment for lateral-torsional buckling: A load acting on the top flange of a bending beam in the direction of the shear center has a destabilizing effect. If, on the other hand, the load pulls on the bottom flange, it has a stabilizing effect. Use the selection fields to define the 'Vertical position'.
Strong buckling axis of built-up compression members
With the 'Do not consider strength reduction factors according to 6.5.5.4.7' check box, you can control whether the strength reduction factors for buckling in the strong axis of the lamellas specified in sections 6.5.5.4.2 to 6.5.5.4.5 may be omitted.
Settings for eigenvalue method
The 'Activate warping stiffness' check box is relevant if the ideal elastic critical moment Mcr is determined using the eigenvalue method. This allows you to control whether the warping resistance Iω is to be considered for lateral-torsional buckling. The warping stiffness is not relevant in the standard.
