# 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

## 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
⩾ 1m/s 1.3 *
crane bridge ⩽ 0.25m/s 1.15 *
⩾ 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:
• Anet is the net area of the cross section.
• fu is the ultimate strength.
• γM2 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, Veff,1,Rd is given by:
(3.9)
where:
• Ant is the net area subjected to tension.
• Anv is the net area subjected to shear.
• fy is the yield strength.
• γM0 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.
• αb 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»!

## 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%)

## 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:

## Advanced service - certified calculation report

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## B1 - Information on the lifting method

 4 2 4.0m 6.0m 4.0m 2.4m 2.4m 63.8° 40mm

## B2 - Forces

country workpiece mass amplification factors design force angle
usage balance slings total
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 L L1 H H1 a c c S355 60.0mm 30mm 60.0mm 227mm 90.0 mm 165mm 90.0mm 90.0 mm 75.0mm 60.0mm 90.0mm

fu = 470MPa
fy = 345MPa

γM0 = 1.0
γM2 = 1.25

## C1 - Lifting lug

### C11 - Tension in the net section

kr = 0.9(EN 1993-1-1 §6.2.3(2.b))
Standard Net area Anet Nu,Rd Gross area A Npl,Rd Nt,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 Nt,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 Anv Veff,Rd Ratio
EN 1993-1-1 §6.2.3 3600 mm2 = 717.07 kN 0.427
Standard Veff,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 : khole = 0.6(EN 1993-1-8 table 3.4 Note 1)
Standard αd αb k1 Fb,Rd Ratio
EN 1993-1-8 §3.6 0.5 0.5 2.5 = 338.4 kN 0.905
Standard Fb,Rd Ratio
EN 1993-1-8 §3.13 = 621.0 kN 0.493

## C2 - Welding

Standard Effective length Lw,eff Fw,Ed (includes eccentricity effects) Effective throat aw βw Fw,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.