Lateral Torsional Buckling Check (Eurocode 3)

Calculate your steel beam's design resistance to lateral torsional buckling with this EN 1993-1-1 compliant tool.

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Input values

Length L

Beam profile options not available.

Material type

LTB values

Free standing load

Lateral restrains at end supports

Fully restrained Beam LTB fork support

Bottom fixed Beam LTB bottom fixed support

Compression only Beam LTB bottom compression only support

Lateral restraints

No restrain

Fully restrained

Enter position

Enter buckling length

Load application

Custom C1 factor

Point loads

ID	x (mm)	F_z,Ed (kN)
F_0,Ed

Distributed loads

ID	x₀ (mm)	x₁ (mm)	q_0,Ed (kN/m)	q_1,Ed (kN/m)
q_0,Ed

Default values

Cross-section class

Partial safety factor γ_M1

Load schema

Results

Max shear:

Max moment:

Max displacement:

Support reaction left:

Support reaction right:

Cross-section class

Required class:

Applied class:

Moment capacities

Effective design moment (M_Ed):

- kNm

Characteristic moment resistance (M_Rk):

- kNm

Moment buckling resistance (M_b,Rd):

- kNm

Utilized capacity (M_b,Rd/M_Rk):

- %

Design check

Unity check LTB:

Parameters explained

Background

Parameter name	Symbol	Unit	Info text
Length	L	mm	Total beam length.
Load application			Load applied on top flange is a destabilizing load. As the beam starts to buckle, the load moves with it, making the twisting worse. The load applied at the bottom flange is a stabilizing position. The load applied at the shear centre is the neutral position, giving no extra torsional effect during buckling.
Free standing load			A free standing load on top of the beam is a destabilizing load. Practically meaning that if the beam moves sideways then the load can move freely with it. This is only the case if the applied load offers no resistance to lateral movement, for example a free standing brick wall. It is 'No' in case the brick wall rests on a floor, because in this case the floor resists the sideway movement.
C1 factor	C₁	-	Moment distribution factor C1. Default value is 1, which is a safe value and it can be manually increased.
C2 factor	C₂	-	Moment distribution factor C2. Default value is 0.63, which is a safe value only for loads applied to the top. For loads applied to the bottom the conservative value is C2 = 0.
Lateral end supports			Describes the lateral restraint conditions at the beam's end supports.
Intermediate lateral restraints			Describes the lateral restraint conditions along the beam's length. For this calculation only restraints applied to the compresive side of the beam do count. The warping length is set equal to the longest unconstrained beam length.
Partial factor for stability	γ_M1	-	Partial factor for stability.
Design bending moment	M_Ed	kNm	Design bending moment.
Characteristic moment resistance	M_Rk	kNm	Characteristic moment resistance.
Moment buckling resistance	M_b,Rd	kNm	Moment buckling resistance.
Unity check	UC	-	The ratio of the design load to the lowest design buckling resistance. A value less than or equal to 1.0 indicates that the design is acceptable under the given load.

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Parameter name

Symbol

Unit

Info text

Length

Total beam length.

Load application

Load applied on top flange is a destabilizing load. As the beam starts to buckle, the load moves with it, making the twisting worse. The load applied at the bottom flange is a stabilizing position. The load applied at the shear centre is the neutral position, giving no extra torsional effect during buckling.

Free standing load

A free standing load on top of the beam is a destabilizing load. Practically meaning that if the beam moves sideways then the load can move freely with it. This is only the case if the applied load offers no resistance to lateral movement, for example a free standing brick wall. It is 'No' in case the brick wall rests on a floor, because in this case the floor resists the sideway movement.

C1 factor

C₁

Moment distribution factor C1. Default value is 1, which is a safe value and it can be manually increased.

C2 factor

C₂

Moment distribution factor C2. Default value is 0.63, which is a safe value only for loads applied to the top. For loads applied to the bottom the conservative value is C2 = 0.

Lateral end supports

Describes the lateral restraint conditions at the beam's end supports.

Intermediate lateral restraints

Describes the lateral restraint conditions along the beam's length. For this calculation only restraints applied to the compresive side of the beam do count. The warping length is set equal to the longest unconstrained beam length.

Partial factor for stability

γ_M1

Partial factor for stability.

Design bending moment

M_Ed

kNm

Design bending moment.

Characteristic moment resistance

M_Rk

kNm

Characteristic moment resistance.

Moment buckling resistance

M_b,Rd

kNm

Moment buckling resistance.

Unity check

The ratio of the design load to the lowest design buckling resistance. A value less than or equal to 1.0 indicates that the design is acceptable under the given load.