Title: Design and Construction Overview of Offshore Concrete Gravity-Based-Structures: Past, Present, and Future
Author(s): Widianto; Jameel Khalifa; Erik Åldstedt; Kåre O. Hæreid; Kjell Tore Fosså
Publication: Symposium Paper
Appears on pages(s): 1-20
Keywords: Floating Construction, Reinforced Concrete Design, D-regions, Structural Analysis, Offshore Structures, Strut-and-tie, Wave loads
An offshore concrete Gravity-Based-Structure (GBS) is a massive concrete structure placed on the seafloor and held in place strictly by its own weight, without need for anchors. This paper focuses on concrete GBSs used as the base of integrated oil drilling and production platforms. The summary of key distinct structural features of several major GBSs, since the first Ekofisk GBS (installed in the North Sea, offshore Norway, in 1973) until the latest Hebron GBS (installed in the Grand Banks, Canada, in 2017), is presented. This paper also discusses several unique loads that GBSs have to resist. An overview of structural analysis and design methodology is described in detail. Key considerations for preliminary sizing of GBS structural components are presented. Typical construction phases, methods, and the importance of constructability are explained. Finally, potential future research topics that would result in a more cost-effective offshore concrete GBS are discussed.