In stability analysis, all these connection layouts are not considered as lateral and torsional restraints, but as torsional springs.
RF-/STEEL EC3 offers the following options to take this into account:
~ When using the Equivalent Member Method, you can either adjust the lateral-torsional buckling length Lw in Window 1.5 or 1.6 (see [3] and [4]), or enter the elastic critical moment for lateral-torsional buckling directly (see [1], [2], and [3]). To do this, change the determination of the elastic critical moment for LTB in the "Details" dialog box, "Stability" tab.
~ When using the General Method, you can enter the torsional spring φX' directly in Window 1.7. For notes on the torsional spring calculation, see [1] and [3].
Reference:
[1] Kuhlmann, Feldmann, Lindner, Stroetmann: Eurocode 3 - DIN EN 1993-1-1 with NA - Commentary and Examples, Beuth publishing house, Ernst & Sohn, 1st Auflage 2014, S. III - 147 ff.
[2] Kuhlmann (Ed.): Stahlbau-Kalender 2009, Ernst & Sohn, p. 335 ff.
[3] Mensinger, Möller: Einfluss von Querkraftanschlüssen auf das Biegedrillknicken von Einfeldträgern - Teil 2, Stahlbau 83 (2014), magazine 3, p. 174 ff.
[4] The Steel Construction Institute and The British Constructional Steelwork Association: Simple Joints to Eurocode 3, 2011, p. 20
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