Container Stack Collapse

Container stack collapse is the structural failure of a deck or hold stack in which the securing arrangement is overwhelmed and one or more bays come down. It is the mechanism by which almost every large container loss at sea actually occurs, and it is distinct from the ship motion that precipitates it.

The sequence runs from acceleration to load to failure. Transverse and vertical accelerations at the outboard top tiers generate racking forces on the container frames, compression on the corner posts of the lower tiers, and tension and shear in the twistlocks and lashing rods. Failure begins at whichever element reaches its limit first, and the loss of one stack transfers load to its neighbours, so collapses propagate along a bay.

Investigators reconstruct the sequence bay by bay from the pattern of what remained, the deformation of the surviving fittings and the recovered stowage plan. The method is common to the reports of the United Kingdom, Australian, French and Japanese investigating bodies.

The full article will cover the load path through a stack, racking and compression limits, the role of container weight misdeclaration, the effect of stack height and tier weight distribution, the forensic method used to reconstruct a collapse, and the interaction with parametric and synchronous rolling.