How FEA Software can Help to Design for Safety
In Rotterdam on July 10th 2008 a tower crane collapsed for no apparent reason tragically causing the death of the crane operator. The construction site suffered extensive damage as a result of the falling structure, and with a footpath and children’s play area nearby, there could have been many more injuries or fatalities.
In the subsequent investigation, consulting company and Siemens PLM Software partner FEMTO Engineering was called upon to simulate the structural failure to determine the cause of the collapse. FEMTO used Femap with NX Nastran to model the crane under various loading conditions and predicted a failure mechanism that corresponded to the sequence of the crane’s collapse.
Alarmingly, the simulation also showed that the flexibility of the crane jib was larger than assumed in the manufacturer’s calculations, a factor which directly led to overloading and subsequent failure of the crane tower. 
The incident and investigation are documented in the Dutch Safety Board report, and you can see a short video showing this simulation where the finite element model has been superimposed on a photograph of the actual building.
The report itself cites several crane failures in Europe in recent years, and quotes an average of seven fatalities and several injuries caused each year by construction crane collapses in the Netherlands alone. Clearly there is scope to perform more simulation at the design stage for structures like these (rather than for post-failure investigations). It seems to me that such incidents can easily be avoided through the use of a careful design approach and the application of simulation software.
Alastair
