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Flexural Torsional Buckling Design


Ag : Gross cross-sectional area of member

Cw : Warping constant, in.6 (mm6)

E: Structural steel modulus of elasticity

Fcr : Critical stress

Fe : Elastic buckling stress determined according to Equation 8.6

Fey : Elastic buckling stress in buckling limit state with bending around the y-axis

Fez : Elastic buckling stress in torsional buckling limit state z-axis

Fy : Specified minimum yield stress of the type of steel being used

G: Shear modulus of elasticity of steel = 11,200 ksi (77 200 MPa)

H: Flexural constant

K : Effective length factor

L: Laterally unbraced length of the member

i: Radius of inertia

Flexural Torsional Buckling Limit State

  • When symmetry axis is the y-axis, where the buckling around the y-axis is caused by the bending and rotation of the element around its longitudinal axis on the Double-Leg angle, T profile, U profile and Single Equal-Leg angle sections that are under compression around their symmetry axes.

Design with ÇYTHYE 2018

  • The compressive strength of the elements is determined according to the axial force acting into the center of gravity section.

  • With the symmetry axis being the y-axis, the elastic buckling stress Fe in the flexural-torsional buckling limit state where buckling around the y-axis occurs by bending and rotating around the longitudinal axis, Fe is calculated according to equation 8.6.

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