FEMA approaches in seismic assessment of jacket platforms (case study: Ressalat jacket of Persian gulf)

Golafshani, Ali Akbar; Tabeshpour, Mohammad Reza; Komachi, Younes

doi:10.1016/j.jcsr.2009.06.005

Cited by 29 publications

(10 citation statements)

References 6 publications

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“…Present guidelines underestimate the outcome due to shipside impacts. Structures may lose all strength and collapse due to failure of a single member . If the location of damage occurs in members near the sea level, the safety factor decreases significantly .…”

Section: Introductionmentioning

confidence: 99%

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A novel hybridized metaheuristic technique in enhancing the diagnosis of cross‐sectional dent damaged offshore platform members

Punurai

Azad

Pholdee

et al. 2019

Computational Intelligence

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Offshore jacket platforms are widely used for oil and gas extraction as well as transportation in shallow to moderate water depth. Tubular cross‐sectional elements are used to construct offshore platforms. Tubular cross sections impart higher resistance against hydrodynamic forces and have high torsional rigidity. During operation, the members can be partially or fully damaged due to lateral impacts. The lateral impacts can be due to ship collisions or through the impact of falling objects. The impact forces can weaken some members that influence the overall performance of the platform. This demonstrates an urgent need to develop a framework that can accurately forecast dent depth as well as dent angle of the affected members. This study investigates the use of an adaptive metaheuristics algorithm to provide automatic detection of denting damage in an offshore structure. The damage information includes dent depth and the dent angle. A model is developed in combination with the percentage of the dent depth of the damaged member and is used to assess the performance of the method. It demonstrates that small changes in stiffness of individual damaged bracing members are detectable from measurements of global structural motion.

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Section: Introductionmentioning

confidence: 99%

“…Structures may lose all strength and collapse due to failure of a single member. 12 If the location of damage occurs in members near the sea level, the safety factor decreases significantly. 13 On the contrary, the structures become unstable if there is damage in the members close to the foundation.…”

Section: Introductionmentioning

confidence: 99%

A novel hybridized metaheuristic technique in enhancing the diagnosis of cross‐sectional dent damaged offshore platform members

Punurai

Azad

Pholdee

et al. 2019

Computational Intelligence

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“…Some researchers [6] considered nonlinear static analyses considering pile soil interaction to assess real fixed jacket platforms. Golafshani et al [7] showed the legs of jacket behavior are force control behavior at first and second level, while its response is deformation controlled behavior at higher levels. The response from bracings exceeded the collapse prevention level at the fourth level while it just passed the life safety level at other levels of the jacket platform.…”

Section: Introductionmentioning

confidence: 99%

Effects of Redundancy in Bracing Systems on the Fragility Curve Development of Steel Jacket Offshore Platform

Azad¹,

Punurai²,

Sinsabvarodom³

et al. 2019

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Steel jacket offshore platforms are typically employed for use in shallow to moderate water depths. During platform operations, there have been some historical accidents completely damaging the diagonal members of the bracing systems due to explosions, fire accidents and dropped objects. Different locations of damaged bracings demonstrate different levels of risk for safety and integrity of the structures. This research illustrates the effects of redundancy in the bracing systems for steel jacket offshore platforms. Assessments have been carried out using the nonlinear pushover analysis method and formations of nonlinear hinges of different members were noted. Redundancy in different positions has been considered to investigate the consequences. Reserve strength ratio (RSR) and damage strength ratio (DSR) of the global structure were also evaluated to understand the importance of different local members. From the collapse data of local failures, fragility curves for the global structures were estimated. The results demonstrated that the position of damage can be a great concern which affects the overall performance of the structures.

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“…The ultimate strength and nonlinear dynamic behavior of JTOPs subjected to earthquake ground motions have been the subject of a number of research papers in recent years. However, many of the previous works have used static pushover procedure to evaluate ultimate capacity, seismic reliability, and seismic assessment of offshore platforms under earthquake load patterns (Gates et al [1], Kayvani and Barzegar [2], Mortazavi and Bea [3], Asgarian and Agheshlui [4], and Golafshani et al [5]). The ultimate strength, hysteretic response of tubular members, and cyclic inelastic behavior of jacket frames of JTOPs ignoring pile foundation part were investigated in the works of Zayas et al [6], Kayvani and Barzegar [2], Mortazavi and Bea [3], Honarvar et al [7], and Golafshani et al [8] using experimental results of frames tested under monotonic increasing static loads or pseudo static cyclic displacement histories.…”

Section: Introductionmentioning

confidence: 99%

Ultimate Strength of Fixed Offshore Platforms Subjected to Near-Fault Earthquake Ground Vibration

Sharifian

Bargi

Zarrin

2015

Shock and Vibration

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The pile foundation nonlinearity and its influence on the ultimate capacity of fixed platforms have not comprehensively been covered by previous researchers. In this study, the seismic behavior and capacity of a newly designed and installed Jacket Type Offshore Platform (JTOP) located in the Persian Gulf is investigated by conducting Incremental Dynamic Analysis (IDA) using a suit of near-fault ground motions. Additionally, two modified models of the original platform are created by slightly increasing the diameter of the pile foundation and also softening the jacket part for evaluating the importance of the pile foundation and seismic soil-pile structure interaction on the dynamic characteristics of the JTOPs. Valuable discussions are provided to explore various aspects of the dynamic behavior of JTOPs by presenting individual and multirecords IDA curves using effective Engineering Demand Parameters (EDPs). Comparing the results of the three platform collapse fragility curves, it is concluded that the pile foundation plays a very important role in the dynamic response of offshore platforms and can drastically alter the ultimate strength of the platform together with its collapse capacity. It is observed that the proportional distribution of nonlinear behavior in the pile foundation and jacket part is the key factor in the enhancement of the ultimate strength of JTOPs. On the basis of the results derived from this paper, it is recommended that some basic requirements should be developed in order to ensure that the coupling ductility of pile foundation and jacket part is optimized during the design process. Furthermore, according to the findings from this study, some practice recommendations are presented to be devised within the design step.

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FEMA approaches in seismic assessment of jacket platforms (case study: Ressalat jacket of Persian gulf)

Cited by 29 publications

References 6 publications

A novel hybridized metaheuristic technique in enhancing the diagnosis of cross‐sectional dent damaged offshore platform members

A novel hybridized metaheuristic technique in enhancing the diagnosis of cross‐sectional dent damaged offshore platform members

Effects of Redundancy in Bracing Systems on the Fragility Curve Development of Steel Jacket Offshore Platform

Ultimate Strength of Fixed Offshore Platforms Subjected to Near-Fault Earthquake Ground Vibration

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