Light Weight Design of Offshore Topside Steel Structures

摘要

The main weight component of the topside of an offshore structure is the structural steel. This study has been performed in order to find out how much the structural steel weight of a typical offshore topside can be reduced. In order to get a reference for comparison an already designed platform has been studied. The studies have shown that it is possible to significantly reduce the weight of the load carrying parts of conventionally designed topside steel structures by: increase in yield strength of the steel material used; improved stiffener arrangements; utilizing corrugated plates. Typical weight reductions of 15-30 % were obtained by replacing the original High Strength (HS) steel having a yield stress of 325-340 MPa with Extra High Strength (EHS) steel with a yield stress of 500 MPa. The increase in dynamic stress levels due to the reduced thickness did not cause any significant fatigue problems. Modification of stiffener arrangements for the Module Support Frame were shown to significantly reduce the weight. By utilizing corrugated plates (designed with an alternative method) as walls in living quarters instead of stiffened panels a weight reduction of about 25 % was shown to be possible. The main conclusion from the project is that it is possible to significantly reduce the steel weight of conventionally designed topside steel structures for offshore installation by utilizing steels of higher strength, and also for some parts by using corrugated walls instead of stiffened plate panels. (ERA citation 14:013368)