Offshore installations must be built to resist fatigue as well as extreme forces caused by severe environmental conditions. The structural reliability analysis is the popular practise to assess a variety of natural waves determined by the long-term probability distribution of wave heights and corresponding periods on the site. In truth, however, these structures are subjected to arbitrary wave-induced forces in the open ocean. Hence, it is much more reasonable to account for the changed loading characteristics by determining the probabilistic characteristics of the random loads and outcomes responses. The key challenges are uncertainties and the non-linearity of Morison’s drag element, which results in non-Gaussian loading and response distributions. This study would analyze advances achieved to date in a comprehensive probabilistic review of offshore fixed jacket-type platforms.

The structural integrity of offshore platforms is affected by degradation issues such as subsidence. Subsidence involves large settlement areas, and it is one of the phenomena that may be experienced by offshore platforms throughout their lives. Compaction of the reservoir is caused by pressure reduction, which results in vertical movement of soils from the reservoir to the mud line. The impact of subsidence on platforms will lead to a gradually reduced wave crest to deck air gap (insufficient air gap) and cause wave-in-deck. The wave-in-deck load can cause significant damage to deck structures, and it may cause the collapse of the entire platform. This study aims to investigate the impact of wave-in-deck load on structure response for fixed offshore structure. The conventional run of pushover analysis only considers the 100-year design crest height for the ultimate collapse. The wave height at collapse is calculated using a limit state equation for the probabilistic model that may give a different result. It is crucial to ensure that the reserve strength ratio (RSR) is not overly estimated, hence giving a false impression of the value. This study is performed to quantify the wave-in-deck load effects based on the revised RSR. As part of the analysis, the Ultimate Strength for Offshore Structures (USFOS) software and wave-in-deck calculation recommended by the International Organization for Standardization (ISO) as practised in the industry is adopted to complete the study. As expected, the new revised RSR with the inclusion of wave-in-deck load is lower and, hence, increases the probability of failure (POF) of the platform. The accuracy and effectiveness of this method will assist the industry, especially operators, for decision making and, more specifically, in outlining the action items as part of their business risk management.

An offshore structure is operated in an ocean wave environment that is stochastic in nature. Essential knowledge of ocean wave mechanics is practically important when it comes to the reliability of the structure. This paper summarised the numerical formulation involved in representing the ocean wave which will provide interaction effect in the design load of offshore structural response. Mechanism of wave load involved the formulation of wave spectra, ocean wave theory, water particles kinematics above sea water level, and the evaluation of wave force. Several formulations introduced by previous researchers for each process of wave load mechanism are discussed. At the end of this study, a good understanding of the estimated wave loads-induced responses will be discovered in terms of the selected ocean wave modelling. In application perspective, the calculated offshore structural responses would be utilised as the design load (structural responses) in structural reliability analysis of offshore platforms.

The reliability of offshore structure is dominantly affected by the wind-generated random waves load. Hence, an appropriate technique is required in predicting the extreme response due to the dominant load. Monte Carlo (MC) time simulation is said to be the most accurate technique. However, such analysis leads to a large number of response records which is computationally demanding. Current finding shows that a modified finite-memory nonlinear system offered more efficient technique. Still, the accuracy is getting severe once negative current is considered. Hence, improved version of MFMNS technique is required by modelling the residue between the extreme values from MC and the approximate MFMNS techniques; known as the eMFMNS technique. In advanced, a comprehensive study on eMFMNS technique will be carried out involving a wide range of environmental conditions. From the investigation, it is proven that eMFMNS technique improved the accuracy in predicting extreme values compare to MFMNS technique.

Offshore structures are exposed to random wave loading in the ocean environment. The response is commonly non-Gaussian due to the nonlinearity of the drag component of Morison's wave loading and also the load intermittency on members in the splash zone. The previous study shows that the developed finite-memory nonlinear system (FMNS) model can efficiently simulate the response of an offshore structure to random Morison wave loading. However, the FMNS models minimise the computational effort, and the estimates are not particularly good for lower significant wave height value. To overcome this deficiency, a modified version of FMNS models (MFMNS) is used to compute the extreme response values which increase the accuracy but is computationally less efficient than the current FMNS models. In this study, the probability distributions of extreme responses from both models are compared with corresponding distributions from the conventional time simulation technique to establish their level of accuracy.

In Malaysia, the majority of oil & gas platform construction use fixed type substructure such as jacket type platform. To date, only one Semi-FPS has been constructed in Malaysia involving complex and challenging issues in the construction of hull substructure. Oil & gas project managers have difficulty to construct the hull and meet the project deadline due to lack of experience in shipbuilding knowledge. The aim of this paper is to define the work breakdown structure and to understand the linkages between work breakdown structure and man-hours development for actual shipbuilding project constructed at Malaysian shipyard, as it is the best tool to simplify the complexity of the project and define the complete and accurate work breakdown structure of a hull ship since it is an important and critical activity in every shipbuilding and Semi-FPS project. The methodology will involve the selection of actual Semi-FPS hull shipbuilding construction case study. The work breakdown structure and project man-hours development will be compared with the latest literature review. The investigation shows that the Product Work Breakdown Structure (PWBS) is the best method in identifying project man-hours in Hull Shipbuilding while the man-hours comparison shows the lower percentage of errors, i.e., 6.36% and 8.77% for the Hull Shipbuilding Structure parts. This concluded the acceptance of Estimator’s Man-hours formula that used in the project case study which does not show any significant error when compared to Industrial Reference, i.e. Spon’s Fabrication Norms for Offshore Structure. The lower Man-hours results compared to the Theoretical value will make the project more competitive and lower cost. Thus, this research will assist the Project Manager to have an idea in project schedule planning which will play a critical role during project management to identify the good WBS and project man-hours. This also leads to cost reduction in terms of man-hour optimization when the proper tasks and activities are clearly defined during WBS development.