Abstract
The growing demand for the application of jacket platforms in deep water requires more attention on the assessment of structural reliability. This paper is devoted to the dynamic reliability analysis of jacket platforms subjected to random wave loads with the Monte-Carlo simulation (MCS), in which a sample size of the order of magnitude of 104 to 105 for repeated time–history analyses is required for small failure probability problems, and a duration time up to three hours needs to be considered in the time–history analyses for a specific sea condition. To tackle the difficulty involved in the MCS, the explicit time-domain method (ETDM) is used for the required time–history analyses of jacket platforms, in which truncated explicit expressions of critical responses with regards to the contributing loading terms are first established and then used for numerous repeated sample analyses. The use of ETDM greatly enhances the computational efficiency of MCS, making it feasible for the dynamic reliability analysis of jacket platforms under random wave loads. A jacket platform with 11,688 degrees of freedom was analyzed for the evaluation of dynamic reliability under a given sea condition, indicating the accuracy and efficiency of the present approach and its feasibility to practical structures.
Highlights
Jacket platforms have been widely used in the exploitation of offshore oil and gas.A reliability analysis is of great concern to the design of jacket platforms due to the uncertainties inevitably involved in wave loads and structural resistances [1,2]
As wave loads are dynamic in nature, the static analysis methods are inadequate to account for the dynamic effects associated with jacket platforms, and the first-passage dynamic reliability analysis is of interest in practical applications
An efficient explicit time-domain method (ETDM)-based Monte-Carlo simulation (MCS) was developed for the evaluation of the first-passage system dynamic reliability of jacket platforms subjected to a specific three-hour sea condition
Summary
Jacket platforms have been widely used in the exploitation of offshore oil and gas. A reliability analysis is of great concern to the design of jacket platforms due to the uncertainties inevitably involved in wave loads and structural resistances [1,2]. Over the past few decades, the power spectrum method (PSM) based on the equivalent linearized Morison equation for wave drags [8,9] was frequently adopted for the first-passage dynamic reliability analysis of jacket platforms, in which certain assumptions regarding the probability distribution of the level-crossing number, e.g., the Poisson process assumption or the Markov process assumption, need to be considered [10,11]. Such level-crossing process-based methods can only obtain an approximate solution for component reliability, and for the system reliability problems involving different component failure modes, only the upper and lower bounds of the failure probability can be estimated [12,13]. An engineering example involving a jacket platform with 11,688 degrees of freedom (DOFs) is analyzed for the dynamic reliability under a given sea condition, indicating the accuracy and efficiency of the present approach and its feasibility in practical structures
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