Torsional Buckling Design

Symbols

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 8.5

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)

J: Torsional constant, in.4 (mm4)

K : Effective length factor

L: Laterally unbraced length of the member

Lcz : Effective length of member around the z-axis (= KL)

Ix , Iy : Moment of inertia about the principal axes, in.4 (mm4)

i: Radius of inertia


Torsional Buckling Limit State

  • Buckling occurs when the element rotates around its longitudinal axis. It occurs in positive (+) shaped built-up elements or channel cross-section that are compressive elements consisting of 4 equal leg angle placed back to back.

Design with ÇYTHYE 2018

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

  • The torsional buckling limit state occurs when the element rotates around its longitudinal axis (positive (+) shaped built-up elements or channel cross-section that are compressive elements consisting of 4 equal leg angle placed back to back) and the elastic buckling stress F e is calculated by equation 8.5.


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Flexural Torsional Buckling Design