The effective length coefficient kz controls the lateral displacement uy and the rotation φz at the member ends. The following options are available in the list of the table column:
- kz = 1.0 restrained against lateral displacement uy on both member ends
- kz = 0.7le restrained against displacement uy on both member ends; restraint about z on left member end
- kz = 0.7ri restrained against displacement uy on both member ends; restraint about z on right member end
- kz = 0.5 restrained against displacement uy and restraint about z on both member ends
- kz = 2.0le restrained against displacement uy and restraint about z on left member end; right member end free
- kz = 2.0ri restrained against displacement uy and restraint about z on right member end; left member end free
The warping length factor kw controls the torsion around the member's longitudinal axis ϕx and the warping ω. The list offers the following options:
- kw = 1.0 restrained against rotation around x on both member ends; free to warp on both sides
- kw = 0.7le restrained against rotation around x on both ends; warping restraint on left member end
- kw = 0.7ri restrained against rotation around x on both ends; warping restraint on right member end
- kw = 0.5 torsion and warping restraint on both member ends
- kw = 2.0le restrained against rotation around x and warping ω on left member end; right member end free
- kw = 2.0ri restrained against rotation around x and warping ω on right member end; left member end free
The abbreviations "li" and "ri" refer to the left and right member ends, respectively. The abbreviation "le" always describes the support conditions at the start of the member.
Cantilever Example
A cantilever is subjected to a moment and an axial force.
In design case 1, the support conditions are defined as for a single-span beam with end fork conditions: kz = 1.0 and kw = 1.0. This results in an elastic critical moment for lateral-torsional buckling of 761.14 kNm.
The mode shape shows the lateral-torsional buckling behavior of a single-span beam.
In design case 2, the cantilever's support conditions are defined correctly: kz = 2.0le and kw = 2.0le. The program determines a significantly smaller critical moment of 371.72 kNm.
The mode shape corresponds to that of a cantilever.
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