# Flexural Torsional Buckling Design

**Symbols**

**A _{g} :** Gross cross-sectional area of member

**C _{w} : **Warping constant, in.

^{6}(mm

^{6})

**E: **Structural steel modulus of elasticity

**F _{cr} : **Critical stress

**F _{e} : **Elastic buckling stress determined according to Equation 8.6

**F _{ey} **: Elastic buckling stress in buckling limit state with bending around the y-axis

**F _{ez} **: Elastic buckling stress in torsional buckling limit state z-axis

**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)

**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 F

_{e}in the flexural-torsional buckling limit state where buckling around the y-axis occurs by bending and rotating around the longitudinal axis, F_{e }is calculated according to equation 8.6.