determination lifting capacities at great heights requires new ...eager.one – sterk new approach...

Eager.one – STERK New Approach - All rights reserved 2018.03.20 Sheet 1

Determination lifting capacities at great

heights requires new approach.

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Demands for capacity at height do increase.

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Reasonable footprint and transportable boom dimensions do notincrease.

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Ringer cranes, though better boom stability, are not an option.

• Operational costs too high• Very low mobility• Footprint too big

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Conclusion :Cranes are getting higher with increased slenderness as a result.

What does this mean for the determination of capacities of cranes?

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Since the 2nd order** effect increases for slender (high) cranes, calculations get more complex and more time consuming due to its non-linear (cyclic) character.

** Definition 2nd order effect:Additional loads on the crane induced by geometrical changes.

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Additional sideward bending moment due to change of shape:

2nd order effect!!

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Additional longitudinal bendingdue to change of shape.

2nd order effect

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Large deformations are not “always” of 2nd order!! In some occations the deformations poorly induce “additional” 2nd order loads.

Mainly….. 1st order effect!!

(in this situation because boom notsteep)

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• 2nd order effect increases • Calculations get more complex and

time consuming.• For every boom-, jib length and

lifting radius it requires a cyclic (non linear) calculation to predict the deformations

• These calculation are done by “non linear” FEM (finite element method).

• Satisfying customer needs, when it comes to crane capacity, becomes very slow.

Slender (high) cranes.

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This gave reason for the development of a hand written code, applicable to run different configurations at the same time, without the need for re-modelling.

We called it…………

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Formerly known as :

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consists of 6 parts:

1. Source code STERK A 2. Validation STERK B 3. Manual STERK C

4. Crane STERK D (project based)5. Ratings STERK E (project based)6. Listings STERK F (project based)

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Source code STERK A

600 pages of code, developed in the latest 5 years during approx. 2000 man-hour's.

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Validation STERK (B)

500 pages document that describes the validation of the STERK code with STERK.

Validation

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Validation STERK (B)

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ValidationSTERK (B)

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ManualSTERK (C)

150 pages of guiding for :

• Interpretation of STERK source code• Using STERK during the making of

ratings

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Crane sheet (project based)STERK (D)

Spreadsheet for completely describing the crane (pre-processing).

Every cell has a graphical remark to guide the STERK user.

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Ratings sheet (project based)

STERK (E)

Spreadsheet for completely describing the ratings (post-processing).

Every load chart value( SWL@Radius ) has a remark, describing the critical issue (strength, stability, etc.)

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For every rating-position or configuration a graphical output of the crane can be generated.

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Listings STERK (F) (project based)Complete summary of all results for a single load chart position (SWL@radius ).

Including :

• Deflections• Stresses• Bending moments • Shear forces • Etc,

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Utilisation 2st order.

• short radius• Non-linear calculation• Safeties applied on loads

(limit state method, partialsafeties)

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Utilisation 1st order.

• Large radius• Linear calculation• Safeties applied on final result

(not limit state method)

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Applicable for which type of machines?

• Crawler cranes with lattice structure boom• Telescopic cranes• Excavators.

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Applicable standards

• EN13000• EN13001• EN13852-1• EN13852-2• EN16228• ISO10567• DNV• Lioyd’s

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Thanks for yourtime!