GL ShipLoad

GL ShipLoad was developed as a user-friendly software tool for efficient generation of realistic loads to enable a reliable global FE analysis of containerships. Based on the design-wave approach, this software identifies the most relevant load combinations for dimensioning a ship's structure. By performing first-principle hydrodynamic computations for regular waves, GL ShipLoad determines wave-induced pressure and ship acceleration values. Structural loads result from the acceleration of masses (inertial loads) and from external (wave-induced) pressure. GL ShipLoad models the mass distribution of a ship and its cargo, computes hydrostatic and hydrodynamic wave-induced pressures, and combines both load types to generate balanced, quasistatic load cases.

User-defined selection criteria, such as the maximum total vertical bending moment or maximum torsional moment, specify the waves used for global strength analysis. By choosing loads specified by the Guidelines for Strength Analyses for Ship Structures with the Finite Element Method, the tool can create rulebased envelope curves of global sectional loads by approximation. A large number of wave situations must be analysed to identify the design waves needed. Roll contributes significantly to the initial torsional moment in the fore holds and must be accounted for when analysing aspects such as hatch cover deflection and the corresponding hatch corner stresses.

Performing a structural analysis on this basis involves several tasks:

1.  generating an FE mesh, capturing the structural properties of the hull

2.  selecting two critical loading conditions for structural analysis, usually the maximum and minimum hogging moments in still water

3.  adding grouped masses to the FE model, representing loads related to cargo and consumables

4.  establishing hydrostatic balance for this loading condition

5.  performing a linear calculation of ship motions and accelerations

6.  computing wave-induced pressures acting on the ship's hull, accounting for non-linear adjustments.

7.  generating dynamic balance for the FE model

8.  performing a systematic analysis of different wave situations

9.  selecting the critical design load cases

10.  performing the structural analysis.

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