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L: Laterally unbraced length of the member
Lc : Effective length of the member, (= KL)
r: Radius of gyration
λ: Width-to-thickness ratio for the element as defined in Section B4.1
λr : Limiting the width-to-thickness ratio as defined in Table B4.1a
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The buckling deformations (deflections) all lie in one of the principal planes of the column cross-section. No twisting of the cross-section occurs for flexural buckling.
The limit state of flexural buckling is applicable for axially loaded columns with, doubly symmetric sections such as bars, HSS and round HSS, and I-shapes and singly symmetric sections, such as T- and U-shapes. Flexural buckling is the simplest type of buckling.
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The compressive strength of the elements is determined according to the axial force acting from the section center of gravity. According to the regulation, the flexural buckling limit state is taken into account in all compression elements, regardless of cross-section properties. The equations used for this are given below in order.
First of all, local buckling control should be done. The calculation is made performed to determine whether the elements are compact or non-compact.
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The buckling deformations consist of a combination of twisting and bending about two flexural axes of the member.
The symmetry axis is the y-axis, where the buckling around the y-axis is caused by the tilting and rotation of the element around its longitudinal axis. The limit state of flexural-torsional buckling is applicable to columns with singly symmetric shapes, such as double angle, T- and U-shapes and asymmetric cross-sections.
Design with AISC 360-16
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