NUMERICAL ANALYSIS USING DIFFERENT LEVELS OF COMPLEXITY AND DETERMINATION OF ULTIMATE LIMIT STATE FOR RISER CONNECTION DEVICE

Resumo

In this work, it is presented two methodologies to analyze the Ultimate Limit State (ULS) of a
commonly adopted riser connection device named bell mouth (used to decrease the loads that cause excessive
bending in the riser) as well as numerical models of said structure, which are compared to a benchmark model.
The assessment of the ULS is performed by a standard applicable to steel structures (but not offshore structures)
with two different approaches – a traditional one and a, not commonly used, hybrid methodology. The numerical
models employ the Finite Element Method with different levels of complexity considered, including elastoplastic
behavior, finite deformations and contact formulations (between the bell mouth and cap). Results show an good
agreement between the two different ULS approaches. The numerical models provide acceptable similarity with
the benchmark model, given its simplicity and low computational cost. It is concluded that the combination of
both ULS and numerical analysis may bring a good first iteration in the bell mouth design process.