DEVELOPMENTS IN HEAVY TRANSPORT DESIGN CALCULATIONS

摘要

With continuous development in the Oil&Gas industry, there is an increase of transports of heavier and bigger structures. As these transports tends to reach the structural limits of heavy transport vessels there is a growing demand to perform more detailed transport analyses. The paper addresses developments in heavy transport design calculations from a theoretical and an operational perspective. Both view-points contribute to a more detailed analysis of the transports and increase the safety level. Theoretical developments of design calculations are achieved by means of a so-called "Global Hull Analysis". An integrated finite element model of the transport vessel and cargo ensures that the stiffness interaction between both is accurately represented. Hydrodynamic analysis -combined with the "design wave approach" - is performed to determine critical load cases, containing hull pressures and accelerations. These load cases are input for structural analysis to determine stresses in and support loads between cargo and heavy transport vessel. Developments on the operational side are achieved by means of a fleet wise motion monitoring project gathering motion and weather data. This project increases insight in operational margins during transports. Concluded is that the recorded nowcast significant wave height from almost 1.200.000 nm of data hardly ever exceeds 5.0 [m], giving a significant operational margin for high design sea-states, typically Hs ＞ 7.0 [m]. For low design sea-state the margin is small. The aim is to reach a constant operational margin by increasing the design sea-state at the lower range and reducing the design sea-state at the higher range. This will be implemented in a new design method.