COMPARATIVE DYNAMIC RESPONSE ANALYSIS OF A FIXED OFFSHORE PLATFORM USING DETERMINISTIC AND SPECTRAL WAVE APPROACHES

摘要

This paper investigates numerically the dynamic response of a fixed offshore platform, namely WHP, in a 2D irregular seaway using both deterministic and spectral design wave approaches. The long-crested irregular seaway is defined by Pierson Moskowitz (PM) spectrum with parameters suiting the WHP installation site. The platform dry weight is 10200 tonnes, sitting on 4 legs wellhead structure, and already installed in Hong Long field of Vietnam coast of South China Sea in a location of 45.47 meters water depth. The platform is supported on piles driven through its legs up to 100 meters protrusion into the seabed. The major construction components of WHP platform are prefabricated piles, jacket, deck, topside, helideck, boat-landing, and a number of J-tubes and risers. A 3D finite element model (FEM) of the platform is created to perform a comparative static and dynamic structural analysis of its response. The numerical results obtained from the deterministic and spectral design wave approaches are compared against each other, and partially validated against the actual platform measurements to introduce a reliable and meaningful interpretation of the numerical results. Finally, for the whole effort to be demonstrated efficiently a few conclusions are introduced and some future recommendations are proposed.