B.J. von Morgen
Report 88.3.OS.2244, Transport Engineering and Logistics.
In order to build production platforms, the deck is divided in several modules.
Such a module contains equipment which has a specific function. The module is
constructed on shore at a construction yard. A barge transports the module to
the productionplatform. The installation is done by a crane vessel.
There are different configurations possible to connect the crane hook to the
module. The normal 4-points lift is a configuration in which the slings are
connected directly to the crane hook and module. This configuration is
statically indeterminated, therefore the load on the slings can vary. The use
of spreader beams or lifting frames give a more equal load on the slings.
The weight and centre of gravity determine the load on the slings. Therefore
they must be known accurately. The stiffness of the module and slings play a
part in the distribution of the load on the slings.
A calculation program can be used to calculate the sling loads. The unknown
variables are calculated by means of an iteration process. Because such
programs are not used at present, certifying authorities apply regulations
which are more strict than necessary.
Reports on Transport Engineering and Logistics (in Dutch)
, TU Delft