Torsional Buckling Design

Symbols

A_g : Gross cross-sectional area of member

C_w : Warping constant, in.⁶ (mm⁶)

E: Structural steel modulus of elasticity

F_cr : Critical stress

F_e : Elastic buckling stress determined according to Equation 8.5

F_y : 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

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

I_x , I_y : 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.

Open

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.

Open