The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
Robert G Bea - One of the best experts on this subject based on the ideXlab platform.
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Risk Assessment and Management of Offshore Structures
Safety and Reliability, 2002Co-Authors: Robert G BeaAbstract:AbstractDuring the past 30 years, reliability based risk assessment & management processes have been developed and applied in assessing and maintaining the integrity of a worldwide infraStructure of Offshore Structure systems. These systems are characterized as a combination of Structures, hardware / equipment, operating personnel, organizations, environments and the interfaces between these components. Background on current and future trends in development of comprehensive programs to help improve the quality and reliability of Offshore Structure systems are outlined. The importance and characteristics of human and organizational factors are discussed. A combination of proactive, reactive, and interactive approaches have been developed that employ three strategies to achieve desirable quality and reliability: reduce likelihoods of malfunctions, increase detection and correction of malfunctions, and decrease the effects and consequences of malfunctions. System robustness and fail-safe design are key eleme...
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Risk Assessment and Management of Offshore Structures
Progress in Structural Engineering and Materials, 2001Co-Authors: Robert G BeaAbstract:During the past 30 years, reliability-based risk assessment and management processes have been developed and applied in assessing and maintaining the integrity of a worldwide infraStructure of Offshore Structure systems. These systems are characterized as a combination of Structures, hardware/equipment, operating personnel, organizations, environments and the interfaces between these components. Background on current and future trends in development of comprehensive programs to help improve the quality and reliability of Offshore Structure systems are outlined. The importance and characteristics of human and organizational factors are discussed. A combination of proactive, reactive and interactive approaches have been developed that employ three strategies to achieve desirable quality and reliability: reduce likelihood of malfunctions, increase detection and correction of malfunctions, and decrease the effects and consequences of malfunctions. System robustness and fail-safe design are key elements of the third strategy.
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human and organization factors engineering operating safety into Offshore Structures
Reliability Engineering & System Safety, 1998Co-Authors: Robert G BeaAbstract:Abstract History indicates clearly that the safety of Offshore Structures is determined primarily by the humans and organizations responsible for these Structures during their design, construction, operation, maintenance, and decommissioning. If the safety of Offshore Structures is to be preserved and improved, then attention of engineers should focus on to how to improve the reliability of the Offshore Structure ‘system,’ including the people that come into contact with the Structure during its life-cycle. This article reviews and discusss concepts and engineering approaches that can be used in such efforts. Two specific human factor issues are addressed: (1) real-time management of safety during operations, and (2) development of a Safety Management Assessment System to help improve the safety of Offshore Structures.
Ju H Park - One of the best experts on this subject based on the ideXlab platform.
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robust fault tolerant h control for Offshore steel jacket platforms via sampled data approach
Journal of The Franklin Institute-engineering and Applied Mathematics, 2015Co-Authors: Rathinasamy Sakthivel, K Mathiyalaga, P. Selvaraj, Ju H ParkAbstract:Abstract This paper addresses the issue of robust fault-tolerant sampled-data H ∞ control for a class of uncertain Offshore steel jacket platform systems with input random time-varying delays and linear fractional uncertainties. A new Lyapunov–Krasovskii functional (LKF) is constructed to obtain sufficient conditions under which the uncertain Offshore platform system is robustly asymptotically stable with a disturbance attenuation level γ > 0 . Moreover, Jenson׳s integral inequality and zero valued free weighting matrix are utilized to simplify the derivation of the main results. Linear matrix inequality (LMI) based sufficient conditions are derived to guarantee the robust performance of the considered Offshore steel jacket platform with a disturbance attenuation index. The proposed results can be used to attenuate the external disturbances to make ensure the safety and comfort level of the Offshore Structure. Finally, the results are verified with simulation results to show the effectiveness of the proposed control scheme.
Rathinasamy Sakthivel - One of the best experts on this subject based on the ideXlab platform.
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robust fault tolerant h control for Offshore steel jacket platforms via sampled data approach
Journal of The Franklin Institute-engineering and Applied Mathematics, 2015Co-Authors: Rathinasamy Sakthivel, K Mathiyalaga, P. Selvaraj, Ju H ParkAbstract:Abstract This paper addresses the issue of robust fault-tolerant sampled-data H ∞ control for a class of uncertain Offshore steel jacket platform systems with input random time-varying delays and linear fractional uncertainties. A new Lyapunov–Krasovskii functional (LKF) is constructed to obtain sufficient conditions under which the uncertain Offshore platform system is robustly asymptotically stable with a disturbance attenuation level γ > 0 . Moreover, Jenson׳s integral inequality and zero valued free weighting matrix are utilized to simplify the derivation of the main results. Linear matrix inequality (LMI) based sufficient conditions are derived to guarantee the robust performance of the considered Offshore steel jacket platform with a disturbance attenuation index. The proposed results can be used to attenuate the external disturbances to make ensure the safety and comfort level of the Offshore Structure. Finally, the results are verified with simulation results to show the effectiveness of the proposed control scheme.
Jiabao Yan - One of the best experts on this subject based on the ideXlab platform.
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damage plasticity based numerical analysis on steel concrete steel sandwich shells used in the arctic Offshore Structure
Engineering Structures, 2016Co-Authors: Jiabao Yan, J Richard Y Liew, Xudong Qian, Liang ZongAbstract:Abstract This paper develops a three-dimensional damage plasticity based finite element model (FEM) to study the ultimate strength of the steel–concrete–steel (SCS) sandwich shell Structure under patch loading. The FEM considers complex geometric nonlinearities of hundreds of stud connectors in the Structure, complex interaction between the connectors and concrete, and material nonlinearities of steel and concrete used in the Structure. In the developed FEM, the concrete core material adopts the concrete damage plasticity model to predict the post-peak softening and residual strength; the stud connectors and steel shells adopt a continuum damage model to phenomenologically describe the damage evolution in the steel material. The reasonable agreement between FE analysis and the quasi-static tests on the SCS sandwich shell Structure confirms the accuracy of the FEM in predicting the ultimate shear resistance, load–deflection relationship, cracks in the concrete core, and punching shear failure of the top steel shell. A subsequence parametric study based on the validated FEM investigates the influence of the curvature on the first peak resistance of the SCS sandwich Structure. Finally, the paper validates accuracy of an analytical model on the punching shear resistance of the concrete core of the SCS sandwich shell.
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steel concrete steel sandwich system in arctic Offshore Structure materials experiments and design
Science & Engineering Faculty, 2016Co-Authors: Jiabao Yan, Xuemei Liu, J Richard Y Liew, Xudong Qian, Minhong ZhangAbstract:The gravity based Structure (GBS) with external Steel–Concrete–Steel (SCS) sandwich ice-resistant wall has been developed for the Arctic oil and gas drilling. This paper firstly reported the experimental studies on the mechanical properties of steel and concretes under Arctic low temperature. With the test data, design equations were developed to incorporate the influences of the low temperature on these mechanical properties. Two types of Arctic GBS Structure with flower-conical SCS sandwich shell type and plate type of ice-resistant wall have been developed for the Arctic Offshore Structure. Besides the studies on the materials, two SCS sandwich prototype shells and plates were, respectively, prepared and tested under patch loading that simulated the localized ice-contact pressure. The structural behaviors of the SCS sandwich Structure under patch loading were reported and discussions were made on the influences of different parameters on the structural behavior of the Structure. Analytical models were developed to predict the punching shear resistances of the SCS sandwich Structure through modifying the code provisions. The accuracies of the developed analytical models were checked through validations against 27 tests in the literature. Corresponding design procedures on resistances of SCS sandwich Structure were recommended based on these discussions and validations.
G. Najafian - One of the best experts on this subject based on the ideXlab platform.
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Extreme structural response values from various methods of simulating wave kinematics
Ships and Offshore Structures, 2014Co-Authors: N. I. Mohd Zaki, M. K. Abu Husain, G. NajafianAbstract:In Offshore engineering, the main forces that are loaded onto ocean Structures come from wind-generated random waves. The prediction of wave forces that are applied onto slender cylindrical members is usually based on the Morison's equation, in which the wave force at any section of a member is expressed directly in terms of wave kinematics. It is essential to be able to estimate sensible kinematics at all levels of a Structure to determine accurate prediction of wave forces and corresponding responses of these Structures in a random wave field. Linear random wave theory (LRWT) is the simplest and most often used to simulate water particle kinematics at different nodes of an Offshore Structure from a reference surface elevation record. However, water particle kinematics calculated from LRWT grossly overpredicts the kinematics above the mean water level (MWL). Methods have been introduced to overcome this problem of high kinematics above the MWL, which consists of using linear wave theory (such as Wheeler,...
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Comparison of ‘100-Year’ Response Values From the Design Wave Technique With Those From the Time-Domain Probabilistic Technique
2005Co-Authors: G. NajafianAbstract:For an Offshore Structure, wind, wave and gravitational forces are all important sources of loading. The dominant load, however, is normally due to wind-generated random waves. It can therefore be concluded that accurate estimation of the extreme values of response due to wave and current loading is an important design requirement. A realistic Structure with varying degrees of dynamic response was chosen to investigate the importance of accounting for all the sea states in the evaluation of response extreme values. To this end, the ‘100-year’ extremes for a few selected responses have been calculated by both the deterministic design wave procedure and the fully probabilistic procedure. The comparison indicates that there is acceptable consistency between the predictions of the design wave and the fully probabilistic procedure in the case of quasi-static Structures. On the other hand, it has been demonstrated that in the case of dynamic Structures, the fully probabilistic procedure, in which the contribution of each sea state to the probability of first-excursion failure is accounted for, should be used.
