Choose a chapter

Eurocode 3 - Steel structures

Calculation of a lifting lug for handling

What is a lifting lug ?

A lifting lug is a lifting and handling accessory generally welded to a part to hoist it with a crane / overhead crane hook.
It is possible to buy standard models or to manufacture them yourself with sheet metal.

standard lifting lug

homemade lifting lug

Good to know !

For France, the usage factor can be found on LEGIFRANCE.

Example with French rules :

lifting and handling equipment	lifting speed	dynamic factor	NF EN 1990 factor	usage factor
fixed crane or on rails	⩽ 0.5m/s	1.15 ^*	1.5	4
fixed crane or on rails	⩾ 1m/s	1.3 ^*
crane bridge	⩽ 0.25m/s	1.15 ^*
crane bridge	⩾ 1m/s	1.6 ^*
lifting and transport on flat ground		2
lifting and transport on rough terrain		> 4	1.5	> 6

^* dynamic factor = with ξ = 0.3 for fixed crane or on rails and ξ = 0.6 for crane bridge.

The quantity of effective lifting points may be less than the quantity of real lifting points if the system is not balanced. It is recommended not to exceed 2 effective lifting points in the calculations if no specific balancing system is used.
The force in one lifting point does not necessarily correspond to the mass to be lifted divided by the number of effective lifting points. The inclination of the slings will cause a horizontal reaction that will amplify the force.
The multiplier factor can be calculated as follow :
With α the angle formed between :
- the two slings connecting the most distant points if no specific balancing system is used.
- the two slings connecting points side by side if a specific balancing system is used (like a lifting beam).
no specific balancing system is used

a lifting beam is used
In the case of intensive use of the lifting point, an additional calculation of the fatigue strength must be carried out.

How to calculate a lifting lug ?

Extract of the standard EN 1993-1-1 §6.2.3 Ultimate Limit States - Resistance of cross-sections - Tension

(2.b) the design ultimate resistance of the net cross-section at holes for fasteners :
(6.7)
where:

A_net is the net area of the cross section.
f_u is the ultimate strength.
γ_M2 is the partial factor for resistance of cross-sections in tension to fracture.

Extract of the standard EN 1993-1-8 §3.10.2 Deductions for fastener holes - Design for block tearing

block tearing

(1) Block tearing consists of failure in shear at the row of bolts along the shear face of the hole group accompanied by tensile rupture along the line of bolt boles on the tension face of the bolt group.
(2) For a symmetric bolt group subject to concentric loading the design block tearing resistance, V_eff,1,Rd is given by:
(3.9)
where:

A_nt is the net area subjected to tension.
A_nv is the net area subjected to shear.
f_y is the yield strength.
γ_M0 is the partial factor for resistance of cross-sections whatever the class is.

Extract of the standard EN 1993-1-8 §3.6 Design resistance of individual fasteners - Bolts and rivets

bearing resistance

(Table 3.4 - bearing resistance)
where:

k₁ is a coefficient that takes into account distances to edges perpendicularly to the applied force.
α_b is a coefficient that takes into account the distances to the edges parallel to the applied force.
d is the nominal crane hook diameter.
t is the the thickness of the lifting lug.
the 0.6 factor is added to take into account the effect of 150% oversized hole (like a slotted hole - Note 1 Table 3.4).

Extract of the standard EN 1993-1-8 §3.13 Connections made with pins

(2) Pin connections in which no rotation is required may be designed as single bolted connections, provided that the length of the pin is less than 3 times the diameter of the pin, see 3.6.1. For all other cases the method given in 3.13.2 should be followed :
Geometric requirements :

(Table 3.10 - bearing resistance)
where:

d₀ is the the hole diameter.

Example of results given by the software

See the features of Lifting Point
Available in English/French, otherwise «Google Translate»!

B - Data

See B1 and B3 below.

C - Summary of checkings according to Eurocodes

Failure modes	Checking
Tension in the net section	OK (37.0%)
Fracture beyond the hole	OK (74.0%)
Bearing	OK (90.5%)
Welding	OK (60.1%)

Export of the results as a DXF file

What is a DXF file ?

The DXF (Drawing eXchange Format) is a CAD data file format developed by Autodesk to allow transfer of information from AutoCAD to other programs.
This makes it possible to directly manufacture the part or integrate it into another technical drawing.

DXF viewers

DXF format files can not only be read by commercial software like AutoCAD but also by several Free/Open Source software like:

Online file viewers:
- DXFconverter (choose « Convert to: SVG » for output)
- ShareCAD
- GroupDoc DXF Viewer
With an installation on your computer:

Technical drawing of the lifting lug in DXF format

Technical drawing of a lifting lug automatically generated on eurocodes-tools.com

Advanced service - certified calculation report

Our service is guaranteed by insurance.

B1 - Information on the lifting method

	Real lifting points	4
	Effective lifting points	2
	Slings height	4.0m
	Spacing on length	6.0m
	Spacing on width	4.0m
	Eccentricity on length (towards the left)	2.4m
	Eccentricity on width (rearward)	2.4m
	Slings angle / horizontal	63.8°
	Hook/shackle diameter d	40mm

B2 - Forces

country	workpiece mass	amplification factors				design force	angle
country	workpiece mass	usage	balance	slings	total	design force	angle
	10000kg	4.0	1.4	1.115	6.242	306.18kN	63.8°

B3 - Dimensions of the lifting lug (general orientation: 0.0° / horizontal)

Steel class	S355	parameter a	60.0mm
Thickness t	30mm	parameter c	60.0mm
L	227mm	End distance e₁ = a + 0.5 d_h	90.0 mm
H	165mm	End distance e₁ = a + 0.5 d_h	90.0 mm
L1	90.0mm	Edge distance e₂ = c + 0.5 d_h	90.0 mm
H1	75.0mm	Edge distance e₂ = c + 0.5 d_h	90.0 mm
Hole diameter d_h	60.0mm	External radius	90.0mm

B4 - Steel properties (EN 10025-2 Table 7)

Ultimate tensile strength :f_u = 470MPa
Yield strength :f_y = 345MPa

B5 - Partial factors (EN 1993-1-1 §6.1(1))

Resistance of cross-sections :γ_M0 = 1.0
Resistance of cross-sections in tension to fracture and joints :γ_M2 = 1.25

C1 - Lifting lug

C11 - Tension in the net section

k_r = 0.9(EN 1993-1-1 §6.2.3(2.b))

Standard	Net area A_net	N_u,Rd	Gross area A	N_pl,Rd	N_t,Rd	Ratio
EN 1993-1-1 §6.2.3	3600 mm²	= 1218.24 kN	5400 mm²	= 1863.0 kN	1218.24 kN	0.251

Standard	N_t,Rd	Ratio
EN 1993-1-8 §3.13	= 828.0 kN	0.37

Example - Do not use

C12 - Fracture beyond the hole

Standard	Net area A_nv	V_eff,Rd	Ratio
EN 1993-1-1 §6.2.3	3600 mm²	= 717.07 kN	0.427

Standard	V_eff,Rd	Ratio
EN 1993-1-8 §3.13	= 414.0 kN	0.74

C13 - Bearing

Hole clearance : oversize hole up to 150%(EN 1090-2 §6.6.1)
Associated reduction factor : k_hole = 0.6(EN 1993-1-8 table 3.4 Note 1)

Standard	α_d	α_b	k₁	F_b,Rd	Ratio
EN 1993-1-8 §3.6	0.5	0.5	2.5	= 338.4 kN	0.905

Standard	F_b,Rd	Ratio
EN 1993-1-8 §3.13	= 621.0 kN	0.493

C2 - Welding

Standard	Effective length L_w,eff	F_w,Ed (includes eccentricity effects)	Effective throat a_w	β_w	F_w,Rd	Ratio
EN 1993-1-8 §3.13	150 mm	2.61kN/mm	9 mm	0.9	= 4.34 kN/mm	0.601

The workpiece on which the lifting lug is welded must be of equal or greater steel grade.
Welding must be peripheral and continuous. In no case should the applied forces lead to an opening of the joint around a longitudinal axis passing through the root of the weld bead.

C3 - Conclusion

Maximum work rate: 90.5%, the dimensions and thickness are correct.