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Calculation of lifting lugs for handling

What are lifting lugs ?

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.
Photograph of a standard lifting lug standard lifting lug
Photograph of a homemade lifting lug homemade lifting lug

Good to know !

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

Drawing of 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

Drawing of bearing resistance 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 :
Geometric requirements drawing




(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»!

B1 - Information on the lifting method

3D 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 (to 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
usage balance slings total
French flag 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 L L1 H H1 a c c parameter a 60.0mm
Thickness t 30mm parameter c 60.0mm
L 227mm End distance
e1 = a + 0.5 dh
90.0 mm
H 165mm
L1 90.0mm Edge distance
e2 = c + 0.5 dh
90.0 mm
H1 75.0mm
Hole diameter dh 60.0mm External radius 90.0mm

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

fu = 470MPa
fy = 345MPa

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

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 0.25
Standard Nt,Rd Ratio
EN 1993-1-8 §3.13 = 828.0 kN 0.37

C12 - Fracture beyond the hole

Standard Net area Anv Veff,Rd Ratio
EN 1993-1-1 §6.2.3 3600 mm2 = 717.07 kN 0.43
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 0.9
Standard Fb,Rd Ratio
EN 1993-1-8 §3.13 = 621.0 kN 0.49

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 2.29kN/mm 9 mm 0.9 = 4.34 kN/mm 0.53
  • 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: 90.0%, the dimensions and thickness are correct.

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:

Technical drawing of the lifting lug in DXF format

Technical