An offshore structural design should accurately calculate wave loads and structural responses acting on slender cylinders. The hydrodynamic drag-dominated force was always challenging, hence the hydrodynamic wave loading became a complex solution; it led to a nonlinear relation between the wave force and responses caused by the diffracted and radiated waves, which was included in Morison’s equation. For more consistency in the structural assessment, the linearised drag–inertia force was considered in model development, such as an improved version of the efficient time simulation regression (ETS-Reg) procedure that was introduced. The study aimed to improve the prediction of structural responses using the predetermined linear, polynomial, and cubic regression models. These simulations were performed focusing on high sea state conditions without wave-induced current effects. In order to evaluate the level of accuracy, the recent ETS-Reg models were compared and validated using the Monte Carlo time simulation (MCTS) method. An amended ETS-Reg model, known as the ETS-Reg_LR model, was also compared with the previous results obtained using the conventional ETS-Reg models (ETS-Reg_SE), leading to better structural response calculations.

Nowadays, the data-based method in Structural Health Monitoring (SHM) is widely used in engineering to provide rich information about damage detection. However,

As a preliminary investigation to determine the structure's overall integrity, it is advised to examine the structure using a linear wave theory. It is recommen

This paper reviews the accuracy of design equations of concrete-filled steel tube (CFST) columns given by GB-50,936, AIJ-2008, AS/NZS 2327, and CSA S16-2019 by expanding the design equations of these codes and incorporating the role of the inner tube. An overall analysis compares the accuracy of different codes in predicting the axial capacity of concrete-filled double-skinned tubular column (CFDST) members. Further, the effect of critical parameters on the axial behaviour of CFDST columns, including geometric and material variables, is systematically analyzed for their different ranges. A detailed evaluation is carried out for each code, and the effect of these parameters on axial strength is compared among the codes, assessing the applicability in different ranges of these parameters. The results showed that CSA S16-2019 produced the most conservative predictions (94.6%) while also giving the highest experimental-to-predicted strength ratio (1.33). The findings observed that CSA S16-2019 yielded maximum conservative results (94.6%), but the average of experimental results to code prediction was the highest, i.e., 1.33. GB-50,936, AIJ-2008, and AS/NZS 2327 provided high percentages of unconservative predictions of the axial capacities of CFDST columns. Finally, the CSA S16-2019 was used to develop a new equation by considering the constraint effect of the inner tube on the axial capacity of CFDST columns. The proposed equation produced accurate and conservative predictions for the axial bearing capacities of CFDST columns with an experimental to predicted strength ratio of 1.19, with a coefficient of variance of 0.15. The innovation of this study lies in extending the applicability of international CFST design codes to CFDST columns, systematically evaluating the role of inner tube parameters, including grade matching, assessing yielding and buckling thickness criteria, and proposing a CSA-based modification that explicitly incorporates the inner tube confinement effect. This approach improves the accuracy and reliability of axial capacity predictions while ensuring consistency with international design practice.