Integrality Assessment of Tubular Joints in Aging Offshore Platform Based on Reliability Theory

Lin, Hong; Chen, Guo Ming; Wang, Zheng Fang; Yang, Lei

doi:10.4028/www.scientific.net/amr.532-533.238

Cited by 3 publications

(6 citation statements)

References 5 publications

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“…Most studies in the offshore reliability analysis have been focusing on component reliability analysis over the years where a fatigue limit state or extreme wave limit state was considered to calculate the probability of failure (Aghakouchak & Stiemer 2001, Rajasankar et al 2003, Lin et al 2012.…”

Section: Introductionmentioning

confidence: 99%

System reliability calculation of jacket platforms including fatigue and extreme wave loading

Khalili¹,

Oterkus²,

Barltrop³

et al. 2019

Trends in the Analysis and Design of Marine Structures

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Jacket platforms are redundant structures. Therefore, reliability analysis at system level is more applicable than at component level. Conventionally, system reliability analysis is estimated based on either fatigue loading or extreme environmental loading. The purpose of this study is to perform the structural reliability analysis of a jacket platform under both fatigue and extreme loading. In this study the fatigue limit state is defined based on the crack size, which is obtained by a fracture mechanics approach. The probability of failure for each component is calculated by using Monte-Carlo simulation. Important failure paths are identified by using a searching process. The system failure criterion is evaluated by comparing the platform strength and loading distributions in terms of base shear. In order to define a probabilistic formula for load, a global response surface method is adopted to relate the wave height to the response of the structure. A pushover analysis is also carried out to determine the capacity of the platform. Having calculated the structure strength and loading distributions, the annual probability of failure under extreme wave is calculated and compared to the tolerable probability of failure or target reliability. An application of the approach is presented.

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Section: Introductionmentioning

confidence: 99%

System reliability calculation of jacket platforms including fatigue and extreme wave loading

Khalili¹,

Oterkus²,

Barltrop³

et al. 2019

Trends in the Analysis and Design of Marine Structures

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show abstract

“…Different criteria such as crack size criterion and equivalent fatigue strength criterion have been suggested to describe the fatigue limit state of the tubular joints with cracks [20]. In the crack size criterion, failure occurs, as soon as the crack propagation size is bigger than a critical value, whereas, in the equivalent fatigue strength criterion, failure happens when the stress intensity factor in the crack tip is greater than the fracture toughness.…”

Section: Probability Of Failure Calculationmentioning

confidence: 99%

“…In this study, the crack size is treated as a failure criterion for the reliability calculations. Therefore, the fatigue limit state function is described as [20]:…”

Section: Probability Of Failure Calculationmentioning

confidence: 99%

Updating the Distributions of Uncertain Parameters Involved in Fatigue Analysis

Khalili

Oterkus

Barltrop

et al. 2020

JMSE

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Fatigue is an important failure mode in offshore jacket platforms. To evaluate the fatigue damage, these platforms are periodically inspected during their lifetime. Regarding fatigue damage, the information from inspection consists of crack measurement. A Bayesian framework can be used to update the probability distribution of the crack size. The main purpose of this study is to develop a framework to update the probability distributions of all uncertain parameters involved in the fatigue crack growth analysis. This methodology maximizes the benefit of the inspection results by updating several uncertain parameters involved in the fracture mechanics approach. Two sets of cracks are used to obtain the updated distributions for uncertain parameters; prior cracks and simulated reality cracks. By comparing these cracks, the updated distributions for uncertain parameters are obtained. The updated crack size distribution can be used to update the estimation of the probability of failure. To demonstrate the developed framework, a tubular joint in a specific jacket platform is considered and the framework is applied for that joint. The results of the developed methodology indicate that the updated distributions of uncertain parameters shift towards the simulated reality distributions.

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“…By assuming as a constant parameter [10] and by integrating Eq. (3) from the initial crack size ( ), to the crack size at time ( ), the crack size value at time can be obtained as:…”

Section: Fatigue Reliability Analysismentioning

confidence: 99%

“…It is assumed that failure occurs, as soon as the crack size is bigger than its critical value. Therefore, the fatigue limit state function is described as [10]:…”

Section: Fatigue Reliability Analysismentioning

confidence: 99%

Different Bayesian Methods for Updating the Fatigue Crack Size Distribution in a Tubular Joint

Khalili

Oterkus

Barltrop

et al. 2020

Journal of Offshore Mechanics and Arctic Engineering

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Offshore platforms are prone to fatigue damage. To evaluate the fatigue damage, these platforms are periodically inspected during the in-service lifetime. Inspection activities provide additional information, which includes detection and measurement of crack size. A Bayesian framework can be used to update the probability distribution of the uncertain parameters such as crack size. After updating the distribution of the crack size, it is possible to improve the estimation of joint reliability. The main purpose of this study is to present different methods of Bayesian inference to update the probability distribution of the crack size using the inspection results and to demonstrate how the results are different. Two different methods are presented; analytical (conjugate) and numerical methods. The advantages and shortcomings of each method are discussed. To compare the results of the analytical and numerical methods, two different situations are considered; updating the crack size distribution for a particular joint and updating the crack size distribution for several joints that have almost the same conditions. Although the proposed methodology can be applied to different kinds of structures, an example of tubular joints in a specific jacket platform is presented to demonstrate the proposed approach and to compare the results of two methods.

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Integrality Assessment of Tubular Joints in Aging Offshore Platform Based on Reliability Theory

Cited by 3 publications

References 5 publications

System reliability calculation of jacket platforms including fatigue and extreme wave loading

System reliability calculation of jacket platforms including fatigue and extreme wave loading

Updating the Distributions of Uncertain Parameters Involved in Fatigue Analysis

Different Bayesian Methods for Updating the Fatigue Crack Size Distribution in a Tubular Joint

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