Macro-element modeling of suction caisson subjected to vertical tensile loading via up-scaling soil stress-strain relations

The vertical uplifting response of suction caisson plays a pivotal role in the ability of the jacket foundation to resist the large moment. Although the macro element model, which encapsulates generalized load and displacement relationships in a unified element, is widely utilized to simulate foundation responses, a macro element model tailored for suction caissons considering project-specific foundation geometries and site-specific soil stress-strain curves is currently underdeveloped. This paper addresses this gap by constructing a macro element model for the uplift response of suction caisson. This goal is achieved by deriving the macro element model via up-scaling soil stress-strain relations. Firstly, finite element analyses (FEA), with a verified undrained hyperbolic soil model, are adopted to obtain macro responses of the uplifting suction caisson in undrained clays. Subsequently, using the same hyperbolic hardening relationship and associated flow rules as the constitutive model of soils, an elasto-plastic macro element model for suction caisson subjected to uplift loads is established. The macro model is then calibrated against the computed caisson responses from FEA, leading to the establishment of a scaling law between the parameters of the macro element model and that of the soil constitutive model. Finally, the constructed macro element model undergoes validation against numerical results and centrifuge test outcomes. The assessment affirms that the proposed macro element model, developed via the up-scaling strategy, can effectively represent test responses and serve as a practical alternative to advanced FEA solutions, providing an efficient and reliable design procedure.