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Joško Parunov - One of the best experts on this subject based on the ideXlab platform.
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structural reliability assessment of an oil tanker accidentally grounded in the adriatic sea
ASME 2017 36th International Conference on Ocean Offshore and Arctic Engineering (OMAE2017), 2017Co-Authors: Maro Corak, Joško Parunov, Guedes C SoaresAbstract:The aim of the paper is to present a methodology for the assessment of the structural reliability of an oil tanker damaged in a hypothetical grounding accident in the Adriatic Sea. The grounding accident affects the ultimate Hull Girder capacity in the damaged region, the still water bending moment (SWBM) distribution along the vessel as well as the vertical wave bending moments (VWBM). The extent of the damage on the ship’s Hull after a grounding accident depends on several parameters such as ship`s speed, rock size, penetration depth, longitudinal and transversal location of stranding along the Hull. These parameters are in the present study assumed as random variables, described by probability density functions. Based on defined statistical properties, random realizations of grounding parameters are simulated by Monte Carlo (MC) simulation. For each such random grounding scenario, the damage size is calculated by the surrogate model based on numerical grounding simulations. Residual ultimate strength and SWBM distribution are determined based on the size and location of the damage. VWBM is calculated for average sea state in the area with increased risk of grounding accident in the Adriatic Sea. Structural reliability analysis is employed to determine the safety index with respect to the ultimate Hull Girder failure for salvage period of 12 hours. As each grounding scenario results in different Hull- Girder reliability, histogram of safety indices is obtained representing new measures for the performance assessment of the damaged ship.
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structural reliability assessment of container ship at the time of accident
Proceedings of the Institution of Mechanical Engineers Part M: Journal of Engineering for the Maritime Environment, 2015Co-Authors: Joško Parunov, Jerolim Andric, Maro Corak, Stanislav KitarovicAbstract:Hull Girder reliability assessment of the MSC Napoli at the time of accident is presented. Loads considered in the study are still water bending moments, vertical wave bending moments and whipping bending moments, while structural capacity is represented by the Hull Girder ultimate strength. Load combination between wave and whipping bending moments is considered. The probability of failure is calculated using a first-order reliability method. Sensitivity study is performed in order to investigate influence of the pertinent random variables. The uncertainty model of the basic random variables involved is consistent with the recent proposal by the International Maritime Organization, thus enabling direct comparison of the obtained results with reliability levels proposed by International Maritime Organization.
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residual strength of damaged oil tanker in the adriatic sea
NAV 2012 17th International Conference on Ships and Shipping Research, 2012Co-Authors: Zrinka Buric, Branka Bužančić Primorac, Joško ParunovAbstract:Accidental damages of ships can occur in any number of ways being the two most concerning ones the collision with other ships and hard grounding on seabed. When a ship is damaged, the operators need to decide on immediate repair actions by evaluating the effects of the damage on the safety of the ship by considering simultaneously effects of the damage in the Hull Girder ultimate bending moment and in the applied loads. Recent disaster of the tanker „Prestige“ in 2002 close to the Spanish coast clearly showed that the ship in damaged condition can be broken and sink as the most unfavourable outcome of such accident with likely spillalge of a large amount of oil onboard. The aim of the paper is to investigate if there is possibility of ultimate Hull Girder collapse of damaged oil tanker in the Adriatic Sea. Location and extent of the damage due to grounding or collision are defined according to the ABS document „Guide for Assessing Hull-Girder Residual Strength for Tankers“. Still water bending moments of damaged oil tanker are estimated using data from available references. Wave loads are calculated by seakeeping software applying 3D panel method. The most probable extreme values of the vertical wave bending moment during the towing period of damaged ship is calculated using available wave statistics for the Adriatic Sea. Ultimate vertical bending capacity of the intact and damaged ship are calculated by MARS software and compared with other similar studies. Finally, safety factors against collapse of damaged ship are determined and corresponding conclusions are drawn.
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Hull Girder reliability of a chemical tanker
Marine Technology and Sname News, 2009Co-Authors: Joško Parunov, Maro ĆorakAbstract:The aim of the paper is to calculate Hull-Girder reliability of chemical tanker according to the reliability model proposed by International Maritime Organization (IMO). The probability of Hull-Girder failure is calculated using a first-order reliability method for two operational profiles—one typical for oil tanker and the other one modified in order to reflect differences between oil tanker and chemical tanker. The evaluation of the wave-induced load effects that occur during long-term operation of the ship in the seaway is carried out in accordance with International Association of Classification Societies (IACS) recommended procedure. The stillwater loads are defined on the basis of a statistical analysis of loading conditions from the loading manual. The ultimate collapse bending moment of the midship cross section, which is used as the basis for the reliability formulation, is evaluated by progressive collapse analysis and by single-step procedure. The reliability analysis is performed for “as-built” ship and for “corroded” ship according to corrosion deduction thickness from new Common Structural Rules for double-Hull oil tankers. It is shown that Hull-Girder failure probability of “as-built” chemical tanker is well above the upper reliability bound proposed by IMO, while the “corroded” ship is slightly unconservative since the reliability index is lower than IMO lower reliability bound.
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Effects of Common Structural Rules on Hull-Girder reliability of an Aframax oil tanker
Reliability Engineering & System Safety, 2008Co-Authors: Joško Parunov, C. Guedes SoaresAbstract:This paper aims at quantifying the changes in notional reliability levels that result from redesigning an existing Aframax tanker to comply with the Common Structural Rules (CSR) for double-Hull oil tankers. The probability of structural failure is calculated using the first-order reliability method. The evaluation of the wave-induced load effects that occur during long-term operation of the ship in the seaway is carried out in accordance with the International Association of Classification Societies (IACS)-recommended procedure, while transfer functions are calculated using the sink–source 3D linear method. The still-water loads are defined on the basis of a statistical analysis of loading conditions from the loading manual. The ultimate collapse bending moment of the midship cross section, which is used as the basis for the reliability formulation, is evaluated by progressive collapse analysis and by a single-step procedure according to CSR. The reliability assessment is performed for “as-built” and “corroded” states of the existing ship and a reinforced ship complying with CSR. It is shown that the Hull-Girder failure probability of an Aframax tanker is reduced several times due to the reinforcements according to CSR. Sensitivity analysis and a parametric study are performed to investigate the variability of results with the change of parameters of pertinent random variables within their plausible ranges. Finally, differences between load combination approaches by Ferry-Borges and Castanheta method and Turkstra's rule are investigated.
Torgeir Moan - One of the best experts on this subject based on the ideXlab platform.
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Ultimate Hull Girder strength of a bulk carrier under combined global and local loads in the hogging and alternate hold loading condition using nonlinear finite element analysis
Journal of Marine Science and Technology, 2012Co-Authors: Torgeir MoanAbstract:For bulk carriers in hogging, the most critical situation is the alternate hold loading (AHL) condition with odd numbered holds loaded with high density cargoes and even numbered holds empty. The effect of the local lateral pressure loads should be considered in the assessment of ultimate Hull Girder strength in the hogging and AHL conditions. In the present paper the ultimate strength of a Capesize bulk carrier Hull Girder under combined global and local loads in the hogging and AHL condition is extensively and systematically investigated using nonlinear finite element (FE) analysis with ABAQUS software. Since the bulk carrier used as a reference vessel in this study is an old design we also studied the effect of modified scantlings by multiplying the plate thickness in the bottom structure by a design modification factor (DMF). In particular, it should be noted that a DMF of 1.4 gives a design in accordance with the new CSR rules. Based on the results obtained by nonlinear FE analyses, a practical interaction equation is established between global hogging bending capacity and average external sea pressure over the bottom.
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A proposal of reliability-based design formats for ultimate Hull Girder strength checks for bulk carriers under combined global and local loadings
Journal of Marine Science and Technology, 2011Co-Authors: Hadi K K Amlashi, Torgeir MoanAbstract:The purpose of this paper is to provide a basis for the development of reliability-based design formats for ultimate Hull Girder strength checks for bulk carriers in hogging conditions under combined global and local loading and to estimate implied safety levels in current rule practices for Hull Girders. The effect of alternative definitions of characteristic still-water loads on the safety format and, hence, the safety factors is assessed. The effect of systematic (bias) model uncertainties associated with loads and strength on the reliability measures is investigated.
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ultimate strength analysis of a bulk carrier Hull Girder under alternate hold loading condition part 2 stress distribution in the double bottom and simplified approaches
Marine Structures, 2009Co-Authors: Hadi K K Amlashi, Torgeir MoanAbstract:This is the second of two companion papers dealing with nonlinear finite element modelling and ultimate strength analysis of the Hull Girder of a bulk carrier under Alternate Hold Loading (AHL) condition. The methodology for nonlinear finite element modelling as well as the ultimate strength results from the nonlinear FE analyses was discussed in the companion paper (Part 1). The purpose of the present paper is to use the FE results to contribute towards developing simplified methods applicable to practical design of ship Hulls under combined global and local loads. An important issue is the significant double bottom bending in the empty hold in AHL due to combined global Hull Girder bending moment and local loads. Therefore, the stress distributions in the double bottom area at different load levels i.e. rule load level and ultimate failure load level are presented in detail. The implication of different design pressures obtained by different rules (CSR-BC rules and DNV rules) on the stress distribution is investigated. Both (partially) heavy cargo AHL and fully loaded cargo AHL are considered. Factors of influence of double bottom bending such as initial imperfections, local loads, stress distribution and failure modes on the Hull Girder strength are discussed. Simplified procedures for determination of the Hull Girder strength for bulk carriers under AHL conditions are also discussed in light of the FE analyses.
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ultimate strength analysis of a bulk carrier Hull Girder under alternate hold loading condition a case study part 1 nonlinear finite element modelling and ultimate Hull Girder capacity
Marine Structures, 2008Co-Authors: Hadi K K Amlashi, Torgeir MoanAbstract:This is the first of two companion papers dealing with nonlinear finite element modelling and analysis of the ultimate strength of a bulk carrier Hull Girder under alternate hold loading (AHL) condition. The purpose is to contribute to establishing rational ultimate longitudinal strength criteria for the Hull Girder under combined loading. The focus is on the hogging condition. An important issue is the significant double bottom bending in empty holds in AHL due to combined global Hull Girder bending moment and local loads. The local loads may substantially reduce the strength of the Hull Girder. Different AHL conditions, i.e. fully loaded cargo and (partially) heavy cargo are considered. A critical review of external and internal design pressures for different AHL conditions is accomplished using both CSR-BC rules and DNV rules. A methodology for nonlinear finite element modelling of hold tanks of a bulk carrier under AHL is presented by use of ABAQUS. A mesh convergence study is carried out in order to find the appropriate mesh for the model. The implication of using different design pressures on the Hull Girder strength is assessed. The FE results can be used as a basis for establishing simplified methods applicable to practical design of ship Hulls under combined loadings. This issue is discussed in the companion paper.
Guedes C Soares - One of the best experts on this subject based on the ideXlab platform.
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structural reliability assessment of an oil tanker accidentally grounded in the adriatic sea
ASME 2017 36th International Conference on Ocean Offshore and Arctic Engineering (OMAE2017), 2017Co-Authors: Maro Corak, Joško Parunov, Guedes C SoaresAbstract:The aim of the paper is to present a methodology for the assessment of the structural reliability of an oil tanker damaged in a hypothetical grounding accident in the Adriatic Sea. The grounding accident affects the ultimate Hull Girder capacity in the damaged region, the still water bending moment (SWBM) distribution along the vessel as well as the vertical wave bending moments (VWBM). The extent of the damage on the ship’s Hull after a grounding accident depends on several parameters such as ship`s speed, rock size, penetration depth, longitudinal and transversal location of stranding along the Hull. These parameters are in the present study assumed as random variables, described by probability density functions. Based on defined statistical properties, random realizations of grounding parameters are simulated by Monte Carlo (MC) simulation. For each such random grounding scenario, the damage size is calculated by the surrogate model based on numerical grounding simulations. Residual ultimate strength and SWBM distribution are determined based on the size and location of the damage. VWBM is calculated for average sea state in the area with increased risk of grounding accident in the Adriatic Sea. Structural reliability analysis is employed to determine the safety index with respect to the ultimate Hull Girder failure for salvage period of 12 hours. As each grounding scenario results in different Hull- Girder reliability, histogram of safety indices is obtained representing new measures for the performance assessment of the damaged ship.
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reliability assessment of a tanker using the model correction factor method based on the iacs csr requirement for Hull Girder ultimate strength
Probabilistic Engineering Mechanics, 2015Co-Authors: A.p. Teixeira, Guedes C SoaresAbstract:Abstract The model correction factor method (MCFM) is adopted to assess the reliability of a Suezmax oil tanker considering the ultimate vertical bending moment capacity of the Hull Girder as a limit state. The approach uses the incremental iterative method proposed by the International Association of Classification Societies (IACS) Common Structural Rules (CSR) to evaluate the Hull Girder ultimate strength as a response model that is calibrated iteratively at the design points calculated by the First Order Reliability method (FORM) by means of advanced non-linear Finite Element Analyses (FEA). The considered loads are the still water and the wave-induced bending moments in a typical seagoing operational condition of the oil tanker in the full load and ballast load conditions. First, the predictions of the Hull Girder bending capacities calculated by the IACS-CSR method and by non-linear FEA are compared and then the efficiency of the MCFM for Hull Girder reliability problems is illustrated. It is shown that using semi-empirical response models, which include the important mechanical features with respect to the bending capacity of the ship Hull Girder, the reliability evaluation can be performed with a limited number of non-linear FEAs (less than 10) promoting the application of advanced response and reliability methods to complex structures.
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an experimental study of ultimate torsional strength of a ship type Hull Girder with a large deck opening
Marine Structures, 2003Co-Authors: Guedes C SoaresAbstract:This paper presents the results of an experimental investigation to determine the torsional ultimate strength of a ship-type Hull Girder with a large deck opening. Two models with the same dimensions and scantlings were designed to reflect the possible modes of failure under pure torque. A comparison between nonlinear finite element calculations and the experimental results for the two models is presented. The effect of different assumptions and of the variation of different parameters is studied.
Deyu Wang - One of the best experts on this subject based on the ideXlab platform.
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ultimate strength envelope of a 10 000teu large container ship subjected to combined loads from compartment model to global Hull Girder
Ocean Engineering, 2020Co-Authors: Qinghu Wang, Deyu WangAbstract:Abstract The main objective of this research is to figure out the relationship of the ultimate strength characteristics between the compartment Hull Girder and the global Hull Girder, especially focusing on the ultimate strength envelope of the global Hull Girder of a 10,000TEU ultra large container ship subjected to combined loads, which is one of the most important indexes to quantify the safety margin of the container ship. To achieve these aims, both the compartment Hull Girder and the global Hull Girder are modeled based on true ship Hull Girder's configurations. A series of full-scale nonlinear finite element analyses are performed. In addition, to examine the reliability of the elastic-perfectly plastic material models employed in FEA, similar scale model collapse experiments of a compartment Hull Girder subjected to pure hogging and pure torsion are also presented. Finally, the ultimate strength envelope of the global Hull Girder of the 10,000TEU ultra large container ship subjected to combined vertical bending and torsion is quantitatively obtained, which can characterize the container ship Hull Girder's ultimate strength interactions between vertical bending and torsion and quantify the safety margin of the global Hull Girder of the container ship subjected to combined vertical bending and torsion.
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experimental and numerical investigations of the ultimate torsional strength of an ultra large container ship
Marine Structures, 2020Co-Authors: Qinghu Wang, Chonglei Wang, Jiameng Wu, Deyu WangAbstract:Abstract Structures of ultra large container ships (ULCS) are characterized by large deck openings and low torsional rigidity. It is essential to comprehensively figure out their collapse behaviors under pure torsion with both model experiments and numerical simulations, making an evaluation of their ultimate torsional strength. In this paper, a similar scale model of a 10,000TEU container ship has been designed and manufactured first, in which both geometric similarity and strength similarity are taken into account. Next the collapse behaviors of the test model are detailedly illustrated with both experimentally and numerically obtained results. Then discussions on warping or shear buckling deformations involved in the collapse process of the structure are conducted with extended numerical simulations. Finally, the ultimate torsional strength of the true ship is evaluated according to the similarity theory. Results show that it is the yielding and shear buckling of the side shells that causes the failure of the Hull Girder under pure torsion. Further nonlinear finite element analysis demonstrates that it may either have warping or shear buckling deformations in the torsional collapse process of the Hull Girder with a large deck opening, depending on the local rigidity distribution of side shells, which has a significant effect on the ultimate torsional strength of the Hull Girder.
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numerical investigation of three dimensional Hull Girder ultimate strength envelope for an ultra large container ship
Ocean Engineering, 2018Co-Authors: Chonglei Wang, Jiameng Wu, Deyu WangAbstract:Abstract Ultra large container ship (ULCS) structures feature large deck openings and low torsional rigidity. It is essential to accurately evaluate the maximum loading carrying capacity of ship structures. When the ship sails at an oblique heading in rough sea, the horizontal and torsional moments may approach or even exceed the magnitude of vertical bending moment. In such cases, Hull Girder ultimate strength assessment of container ships under load combinations comprising of vertical bending moment, horizontal bending moment and torsion is necessary in their structural design stage. In this paper, special attentions are thus paid to the Hull Girder ultimate strength of an ULCS (i.e., a typical 10,000 TEU container ship) subjected to combined three load components mentioned above, which is also a common load case in ships and ship-shaped offshore structures and it is assumed that the three kinds of main loads can be combined each other freely. A series of nonlinear finite element analyses (NFEA) is carried out. Effects of fabrication related initial imperfections are investigated in the present study. Based on the computed numerical results, the 3D Hull Girder ultimate strength envelope considering initial deformation and incorporating the interaction relationships among three kinds of load components mentioned above is established.
Hadi K K Amlashi - One of the best experts on this subject based on the ideXlab platform.
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A proposal of reliability-based design formats for ultimate Hull Girder strength checks for bulk carriers under combined global and local loadings
Journal of Marine Science and Technology, 2011Co-Authors: Hadi K K Amlashi, Torgeir MoanAbstract:The purpose of this paper is to provide a basis for the development of reliability-based design formats for ultimate Hull Girder strength checks for bulk carriers in hogging conditions under combined global and local loading and to estimate implied safety levels in current rule practices for Hull Girders. The effect of alternative definitions of characteristic still-water loads on the safety format and, hence, the safety factors is assessed. The effect of systematic (bias) model uncertainties associated with loads and strength on the reliability measures is investigated.
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ultimate strength analysis of a bulk carrier Hull Girder under alternate hold loading condition part 2 stress distribution in the double bottom and simplified approaches
Marine Structures, 2009Co-Authors: Hadi K K Amlashi, Torgeir MoanAbstract:This is the second of two companion papers dealing with nonlinear finite element modelling and ultimate strength analysis of the Hull Girder of a bulk carrier under Alternate Hold Loading (AHL) condition. The methodology for nonlinear finite element modelling as well as the ultimate strength results from the nonlinear FE analyses was discussed in the companion paper (Part 1). The purpose of the present paper is to use the FE results to contribute towards developing simplified methods applicable to practical design of ship Hulls under combined global and local loads. An important issue is the significant double bottom bending in the empty hold in AHL due to combined global Hull Girder bending moment and local loads. Therefore, the stress distributions in the double bottom area at different load levels i.e. rule load level and ultimate failure load level are presented in detail. The implication of different design pressures obtained by different rules (CSR-BC rules and DNV rules) on the stress distribution is investigated. Both (partially) heavy cargo AHL and fully loaded cargo AHL are considered. Factors of influence of double bottom bending such as initial imperfections, local loads, stress distribution and failure modes on the Hull Girder strength are discussed. Simplified procedures for determination of the Hull Girder strength for bulk carriers under AHL conditions are also discussed in light of the FE analyses.
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ultimate strength analysis of a bulk carrier Hull Girder under alternate hold loading condition a case study part 1 nonlinear finite element modelling and ultimate Hull Girder capacity
Marine Structures, 2008Co-Authors: Hadi K K Amlashi, Torgeir MoanAbstract:This is the first of two companion papers dealing with nonlinear finite element modelling and analysis of the ultimate strength of a bulk carrier Hull Girder under alternate hold loading (AHL) condition. The purpose is to contribute to establishing rational ultimate longitudinal strength criteria for the Hull Girder under combined loading. The focus is on the hogging condition. An important issue is the significant double bottom bending in empty holds in AHL due to combined global Hull Girder bending moment and local loads. The local loads may substantially reduce the strength of the Hull Girder. Different AHL conditions, i.e. fully loaded cargo and (partially) heavy cargo are considered. A critical review of external and internal design pressures for different AHL conditions is accomplished using both CSR-BC rules and DNV rules. A methodology for nonlinear finite element modelling of hold tanks of a bulk carrier under AHL is presented by use of ABAQUS. A mesh convergence study is carried out in order to find the appropriate mesh for the model. The implication of using different design pressures on the Hull Girder strength is assessed. The FE results can be used as a basis for establishing simplified methods applicable to practical design of ship Hulls under combined loadings. This issue is discussed in the companion paper.