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Crane runways calculation

What are crane runways ?

Different types of cranes

Photograph of a top mounted crane bridge top-mounted crane bridge
Photograph of an underslung crane bridge underslung crane bridge
Photograph of a monorail hoist block monorail hoist block
The main difference between the configurations of these hoisting devices is the working load limit (WLL); see also «lifting point».
From commercially catalogues of crane bridge suppliers, it is generally found that : Some of the crane bridge suppliers :
ABUS, FAYAT ADC, GH cranes & components, HADEF, KONECRANES, OMIS, SMAK, VERLINDE, ... Your company is not is the list ? Contact us to add it.

Different types of ways

Photograph of commercially available profiles commercially available profiles
Drawing of a reinforced profile reinforced with angles
for top-mounted crane only !
Photograph of a welded reconstructed profile welded reconstructed sections
The crane runways can be fixed to the main frames of the buiding or mounted on independent columns.

How to calculate crane runways ?

Step 1 - Loadings calculation from EN 1991-3

Extract of the standard §2.2.1 Classifications of actions - General

(l)P Actions induced by cranes shall be classified as variable and accidental actions which are represented by various models as described in 2.2.2 and 2.2.3.

Extract of the standard §2.2.2 Classifications of actions - Variable actions

(1) For normal service conditions, variable crane actions result from variation in time and location. They include gravity loads including hoist loads, inertial forces caused by acceleration/deceleration and by skewing and other dynamic effects.
(2) The variable crane actions should be separated into:
  • variable vertical crane actions caused by the self-weight of the crane and the hoist load;
  • variable horizontal crane actions caused by acceleration or deceleration or by skewing or other dynamic effects.
(3) The various representative values of variable crane actions are characteristic values composed of a static and a dynamic component.
(4) Dynamic components induced by vibration due to inertial and damping forces are in general accounted by dynamic factors φ to be applied to the static action values. (2.1)
where:
  • Fφ,k is the characteristic value of a crane action;
  • φi is the dynamic factor, see Table 2.1;
  • Fk is the characteristic static component of a crane action.
(5) The various dynamic factors and their application are listed in Table 2.1.
(6) The simultaneity of the crane load components may be taken into account by considering groups of loads as identified in Table 2.2. Each of these groups of loads should be considered as defining one characteristic crane action for the combination with non-crane loads.
NOTE: The grouping provides that only one horizontal crane action is considered at a time.
Table 2.1 Dynamic factors φi
Dynamic factors Effects to be considered To be applied to
φ1 Excitation of the crane structure due to lifting the hoist load off the ground self-weight of the crane
φ2 Dynamic effects of transferring the hoist load from the ground to the crane hoist load
φ3 Dynamic effects of sudden release of the payload if for example grabs or magnets are used hoist load
φ4 Dynamic effects induced when the crane is travelling on rail tracks or runways self-weight of the crane and hoist load
φ5 Dynamic effects caused by drive forces drive forces
φ6 Dynamic effects of a test load moved by the drives in the way the crane is used test load
φ7 Dynamic elastic effects of impact on buffers buffer loads
Table 2.2 - Groups of loads and dynamic factors to be considered as one characteristic crane action
Symbol Section Groups of loads
Ultimate Limit State Test load Accidental
1 2 3 4 5 6 7 8 9 10
1 Self-weight of crane Qc 2.6 φ1 φ1 1 φ4 φ4 φ4 1 φ1 1 1
2 Hoist load Qh 2.6 φ2 φ3 - φ4 φ4 φ4 η(1) - 1 1
3 Acceleration of crane bridge HL, HT 2.7 φ5 φ5 φ5 φ5 - - - φ5 - -
4 Skewing of crane bridge HS 2.7 - - - - 1 - - - - -
5 Acceleration or braking of crab or hoist block HT3 2.7 - - - - - 1 - - - -
6 In-service wind Fw Annex A 1 1 1 1 1 - - 1 - -
7 Test load QT 2.10 - - - - - - - φ6 - -
8 Buffer force HB 2.11 - - - - - - - - φ7 -
9 Tilting force HTA 2.11 - - - - - - - - - 1
1 η is the proportion of the hoist load that remains when the payload is removed, but is not included in the self-weight of the crane.

Step 2 - Iterative mechanical analysis

Each of the crane bridge longitudinal positions (along the runway) and transversal positions (staggered or skewed wheels with respect to the rail axis) must be analyzed to detect maximum forces and deformations.
We have developed a specific mechanical solver to do exactly this job.

Step 3 - Serviceability Limit States checkings from EN 1993-6

Four main criteria should be checked, the limiting values of : Some other criteria may have to be checked.

Step 4 - Ultimate Limit States checkings from EN 1993-6

For a top-mounted crane bridge :

Extracts of results given by the software

See the features of Crane Runways
Available in English/French, otherwise «Google Translate»!
B2 - Way geometry and section parameters B21 - Runway element
stiffener on support stiffener on support 6.0m
B22 - Cross section
Minimum steel grade of the elements : S275 (fy = 275 MPa, E = 210000 MPa)
Runway section : HEA300
Rail section : 40x30 (the rail is welded on the runway and the wear of the rail of 25% is taken into account in the calculations of the characteristics.)
Travee 1 Mechanical characteristics :
  • Area : A=121.5 cm2
  • Shear areas :
    • on z-z : : Asz=37.3 cm2
    • top flange on y-y : Asy,top=42.0 cm2
    • bottom flange on y-y : Asy,bot=42.0 cm2
  • Second moments of area :
    • about y-y : Iy=20301.8 cm4 (with : : zG = 15.7cm)
    • top flange about z-z : Iz=3166.2 cm4
    • bottom flange about z-z : Iz=3154.2 cm4
  • Second moment of area, about its horizontal centroidal axis, of the combined cross section comprising the rail and a flange with an effective width of beff : Irf=21.8 cm4
  • Torsion constant of the flange (including the rail if it is rigidly fixed) : It=75.4 cm4

F1 - Ultimate Limit States F11 - Stresses and Von Mises criteria §6.2
EN1993-1-1 (6.1)
top flange web top bottom flange flanges middle
Span right above left above right below left below right left right above left above right below left below above below
1 195.4MPa 181.8MPa 187.9MPa 174.7MPa 61.4MPa 130.3MPa 108.4MPa 108.4MPa 116.8MPa 116.8MPa 81.7MPa 95.7MPa
Table F11.a - Maximal Von Mises criteria by span for each of the twelve checking points.
top flange web top bottom flange flanges middle
Span right above left above right below left below right left right above left above right below left below above below
1 0.711 0.661 0.683 0.635 0.223 0.474 0.394 0.394 0.425 0.425 0.297 0.348
Table F11.b - Maximal Von Mises ratio by span for each of the twelve checking points.
F12 - Transverse buckling of the flanges §6.3
EN1993-1-1 (6.60 + 6.61)
F121 - Top flange
Span NEd Mz,Ed kc Lcr,z λf Ncr,z kfl χz Cm,z kzz Ratio Section position Crane position
1 395.6kN 26.1m.kN 0.86 5.16m 0.808 2464.7kN 1.081 0.657 0.969 1.094 0.837 2.7m 2.7m
Table F121 - Maximal buckling ratio by span for top flange.
F13 - Local buckling §6.6 F131 - Local buckling of the flanges EN1993-1-5 §4
EN1993-1-5 (4.14)
top flange
Span My Wel,y Ratio Section position Crane position
1 124.1m.kN 1699.9cm3 0.266 3.6m 0.9m
Table F131 - Maximal local buckling ratio by span for each flange.
F132 - Local buckling of the web under shear EN1993-1-5 §5
EN1993-1-5 (5.10)
Span kτ hw/tw limmax σE τcr λrel,w χw Ratio Section position Crane position
1 5.348 30.824 66.269 hw/tw < limmax : Verification is not needed
Table F132 - Maximal local buckling ratio by span for the web under shear.
F133 - Local buckling of the web under point load EN1993-1-5 §6
EN1993-1-5 (6.14)
Span FEd; ss Fcr λrel,F χF L;eff Ratio Section position Crane position
1 65.9kN 0.127m 2659.8kN 0.544 0.919 0.31m 0.091 3.3m 0.6m
Table F133 - Maximal local buckling ratio by span for the top of the web under point load.
F134 - Interactions EN1993-1-5 §7
EN1993-1-5 (7.2)
Span η2 η1 Ratio Section position Crane position
1 0.091 0.266 0.303 3.6m 0.9m
Table F134.a - Maximal local buckling interaction ratio by span under point load.
si EN1993-1-5 (7.1)
top flange bottom flange
Span η3 Wf,Rd Wpl,Rd η1 Ratio Section position Crane position η1 Ratio Section position Crane position
1 0.0 η3 ≤ 0.5 : Verification is not needed
Table F134.b - Maximal local buckling interaction ratio by span under shear.
F2 - Serviceability Limit States
  • Limiting values of horizontal deflections (EN1993-6 7.1) : L/600
  • Limiting values of vertical deflections (EN1993-6 7.2) : L/600
  • Limiting values for web breathing (EN1993-6 §7.4(3)) : b/tw < 120
  • Limiting values for vibration of the bottom flange (EN1993-6 §7.6(2)) : Lf / if,z ⩽ 250
SLS z SLS y Web breathing Vibration of the bottom flange
Span Abscissa Ratio Abscissa Ratio Ratio Ratio
1 3.0m 0.799 3.0m 0.798 0.257 0.301
Table F2 - Maximal SLS ratios and associate positions by span for each axis.
F3 - Conclusion
Maximum work rate: 83.7%, the section is correct.