What are the most common challenges in stress analysis for offshore structures?

1 Nonlinear behavior

One of the major challenges in stress analysis for offshore structures is the nonlinear behavior of the materials, geometries, and boundary conditions. Nonlinear behavior means that the response of the structure is not proportional to the applied load, and may depend on the loading history, the deformation level, the temperature, and the damage. For example, steel may exhibit plasticity, buckling, fatigue, and fracture; concrete may show cracking, crushing, and spalling; and soil may exhibit consolidation, liquefaction, and shear failure. Nonlinear behavior makes the stress analysis more complex and requires advanced numerical methods and models to capture the physical phenomena accurately.

3 Coupled effects

A third challenge in stress analysis for offshore structures is the coupled effects of different physical domains and mechanisms. Coupled effects mean that the stress response of the structure is influenced by the interaction of multiple factors, such as fluid-structure interaction, soil-structure interaction, thermal-mechanical coupling, and structural-acoustic coupling. For example, the fluid-structure interaction may cause hydrodynamic loads, added mass, damping, and vortex-induced vibrations; the soil-structure interaction may cause foundation stiffness, bearing capacity, and soil-pipe interaction; the thermal-mechanical coupling may cause thermal expansion, contraction, and stress; and the structural-acoustic coupling may cause noise, vibration, and resonance. Coupled effects make the stress analysis more comprehensive and require multiphysics methods and models to account for the interdependence of different domains and mechanisms.

5 Validation and verification

A fifth challenge in stress analysis for offshore structures is the validation and verification of the models and results. Validation and verification mean that the stress analysis is not only based on theoretical and numerical models, but also on experimental and field data. For example, the validation and verification may involve the comparison of the model predictions with the laboratory tests, the field measurements, and the historical data; the identification and correction of the errors, uncertainties, and discrepancies in the models and results; and the assessment and improvement of the accuracy, reliability, and robustness of the models and results. Validation and verification make the stress analysis more realistic and require validation methods and models to ensure the quality and credibility of the stress analysis.

6 Software and tools

A sixth challenge in stress analysis for offshore structures is the software and tools that are used to perform the analysis. Software and tools mean that the stress analysis is not only dependent on the knowledge and skills of the engineers, but also on the availability and functionality of the software and tools. For example, the software and tools may include the finite element software, the computational fluid dynamics software, the probabilistic software, the optimization software, and the validation software; as well as the hardware, the databases, the standards, and the guidelines that support the software. Software and tools make the stress analysis more efficient and convenient, but also require constant updating, learning, and testing to keep up with the advances and challenges in offshore structural engineering.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?