Heavy block, thin deck — 396 t across 24 lugs
A 396-tonne ship block, a deck plate only 6 mm thick, and just three cranes to lift it. Three direct lift points would have driven around 132 tonnes through each connection — far more than a thin deck can take without oversized lugs. Load equalizers solved it; the FE model had to prove they actually share the load.
The problem
The block weighed 396 tonnes, and only three cranes were available. Lifting from three points means roughly 132 tonnes through each connection — and the deck plate the lugs weld to was just 6 mm thick. Putting that much load through three attachments would demand very large lugs and heavy local reinforcement, just to keep the thin plate from tearing. On a real programme that is cost, weight, and fabrication time you do not want.
The approach
Instead of three heavy lift points, the lift used three load equalizers, each feeding eight lugs — 24 modest attachment points spreading the same load across the deck. An equalizer only earns its place if it genuinely shares load equally between its legs, so the model had to represent that behaviour without distorting the structure.
Each equalizer was tied to its eight lugs with a multi-point constraint — an RBE3 element. This is the key modelling choice: an RBE3 distributes the applied load across its connected nodes without adding stiffness to the structure. A rigid RBE2 tie, by contrast, would have bolted those lugs together into an artificial load path and reported a distribution that the real rigging never produces. RBE3 keeps the load-sharing honest.
The proof
Freebody extraction at every lug tells the story: the reaction force is identical for all eight lugs within each equalizer group. The equalizers behave exactly as the rigging intends, and the constraint added no artificial stiffness to the block. Per-lug load comes out around 15.5 tonnes instead of 132 — small enough for a standard, buildable lug on a thin deck. Equal sharing verified, not assumed.
The three equalizer groups differ slightly from one another — that is just the block's centre of gravity, not a modelling artefact. Within each group, the sharing is exact.