Study on the Effect of Climate Change on Ship Responses Based on Nonlinear Simulations

2018 ◽  
Author(s):  
Bingjie Guo ◽  
Odin Gramstad ◽  
Erik Vanem ◽  
Elzbieta Bitner-Gregersen
Keyword(s):  
Climate Change ◽  
Nonlinear Wave ◽  
Structural Reliability ◽  
Failure Modes ◽  
Bending Moment ◽  
Nonlinear Effects ◽  
Wave Model ◽  
Higher Order ◽  
Hull Girder ◽  
Structural Rules

Hull girder ultimate strength, which governs sagging and hogging failures, is one of the most critical failure modes for a ship hull. The Structural Reliability Analysis (SRA) methodology has been used to develop Common Structural Rules (CRS) for tankers and bulk carriers. A linear model for bending moment in extreme weather with a nonlinear correction factor has been adopted in the analysis. It is difficult to conclude on the model uncertainty associated with nonlinear effects of bending moment as, until now, there are very limited studies addressing this topic. In this paper, the nonlinear effect on ship responses will be analyzed, and the potential effect of climate change on ship responses will be investigated with the improved 3D Rankine Panel method using nonlinear wave input. The nonlinear wave input is generated by the HOSM (Higher order Spectral Method) wave model incorporating higher order nonlinear effects, including nonlinear free-wave modulation as well as higher order bound harmonics. The North Atlantic past and projected future wave climates are considered.

Study on the Effect of Climate Change on Ship Responses Based on Nonlinear Simulations

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Bingjie Guo ◽  
Odin Gramstad ◽  
Erik Vanem ◽  
Elzbieta Bitner-Gregersen
Keyword(s):  
Climate Change ◽  
Nonlinear Wave ◽  
Structural Reliability ◽  
Failure Modes ◽  
Bending Moment ◽  
Nonlinear Effects ◽  
Wave Model ◽  
Higher Order ◽  
Hull Girder ◽  
Structural Rules

Hull girder ultimate strength governs sagging and hogging failures, which is one of the most critical failure modes for a ship hull. The structural reliability analysis methodology has been used to develop common structural rules for tankers and bulk carriers. A linear model for bending moment in extreme weather with a nonlinear correction factor has been adopted in the analysis. It is difficult to conclude on the model uncertainty associated with nonlinear effects of bending moment as, until now, there are few studies addressing this topic. In this paper, the nonlinear effect on ship responses is analyzed, and the potential effect of climate change on ship responses is investigated with the improved three-dimensional (3D) Rankine Panel method using nonlinear wave input. The nonlinear wave input is generated by the higher-order spectral method (HOSM) wave model incorporating higher-order nonlinear effects, including nonlinear free-wave modulation as well as higher-order bound harmonics. The past and projected future wave climates of selected locations in the North Atlantic and North Norwegian Sea are considered.

Structural Reliability of a Suezmax Oil Tanker Designed According to New Common Structural Rules

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
C. Guedes Soares ◽  
Joško Parunov
Keyword(s):  
Structural Reliability ◽  
International Association ◽  
Bending Moment ◽  
Single Step ◽  
Hull Girder ◽  
Structural Rules ◽  
Term Operation ◽  
Reliability Method ◽  
Common Structural Rules

The paper aims at quantifying the changes in notional reliability levels that result from redesigning an existing suezmax tanker to comply with new Common Structural Rules (CSR) requirement for ultimate vertical bending moment capacity. The probability of structural failure is calculated using a 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 to International Association of Classification Societies (IACS) recommended procedure. Comparative analysis of long-term distributions of vertical wave bending moment calculated by two independent computer seakeeping codes is performed. 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 CSR single-step procedure and by program HULLCOLL for progressive collapse analysis of ship hull-girders. The reliability assessment is performed for as-built and corroded states of the existing ship and a reinforced design configuration complying with CSR. It is shown that hull-girder failure probability of suezmax tanker reinforced according to new CSR is reduced several times. Sensitivity analysis and a parametric study are performed to investigate the variability of results to the change of parameters of pertinent random variables within their plausible ranges.

Hull-Girder Reliability of a Chemical Tanker

2009 ◽  
Vol 46 (04) ◽  
pp. 192-199
Author(s):  
Jôsko Parunov ◽  
Maro Corak ◽  
C. Guedes Soares
Keyword(s):  
International Association ◽  
Progressive Collapse ◽  
Bending Moment ◽  
Single Step ◽  
Hull Girder ◽  
Structural Rules ◽  
Term Operation ◽  
Reliability Method ◽  
Reliability Bound ◽  
Oil Tanker

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.

The Effect of Sloshing in Tanks on Motions and Hull Girder Responses of Damaged Vessels

2011 ◽  
Author(s):  
Huirong Jia ◽  
Torgeir Moan
Keyword(s):  
Reliability Analysis ◽  
Structural Reliability ◽  
Bending Moment ◽  
Roll Motion ◽  
Multimodal Approach ◽  
Rectangular Shape ◽  
Hull Girder ◽  
Structural Reliability Analysis ◽  
Oil Tankers

The structural reliability analysis of damaged vessels has up to now commonly been investigated by neglecting the effect of sloshing. This paper deals with the effect of sloshing in tanks on motions and hull girder responses of oil tankers in various damage conditions and represents a part of a study to assess the effect of sloshing on hull girder failure of damaged vessels, The flooded tanks are assumed to have a of rectangular shape and linear multimodal approach is adopted to deal with sloshing. It is concluded that even though the effect of sloshing in tanks on the roll motion of vessels can be neglected in certain damage conditions, the effect of sloshing on the horizontal bending moment cannot be neglected, especially when resonance motion occurs.

Evaluation of IACS Common Structural Rules in Terms of Ultimate Limit State Design and Assessment of Ship Structures

2007 ◽  
Author(s):  
Jeom Kee Paik ◽  
Bong Ju Kim ◽  
Jung Kwan Seo
Keyword(s):  
Limit State ◽  
Bending Moment ◽  
Ultimate Limit State ◽  
Stiffened Plate ◽  
Plate Structures ◽  
Hull Girder ◽  
Structural Rules ◽  
Out Of Plane ◽  
Common Structural Rules ◽  
Ultimate Limit

The aim of the present paper is to evaluate the ultimate limit state performance of an AFRAMAX-class hypothetical double hull oil tanker structure designed by IACS CSR (Common Structural Rules) method, compared with the same-class/type tanker structure designed by IACS pre-CSR method. The ultimate strengths of stiffened plate structures in deck and bottom parts under combined in-plane and out-of-plane actions, and hull girder against vertical bending moment, are computed for the two designs, and the resulting computations are compared. ALPS/ULSAP program is used for the ultimate limit state assessment of stiffened plate structures, while ALPS/HULL program is employed for the progressive hull collapse analysis. ANSYS nonlinear FEA method, which uses more refined technology, is also used for the same purpose. The insights and developments obtained from the present study are addressed.

Structural Reliability of a Suezmax Oil Tanker Designed According to New Joint Tanker Project Rules

2006 ◽  
Author(s):  
C. Guedes Soares ◽  
Josˇko Parunov
Keyword(s):  
Structural Reliability ◽  
Progressive Collapse ◽  
Bending Moment ◽  
Single Step ◽  
Moment Capacity ◽  
Hull Girder ◽  
Term Operation ◽  
Reliability Method ◽  
Wave Induced

The paper aims at quantifying the changes in notional reliability levels that result from redesigning an existing suezmax tanker to comply with new Joint Tanker Project (JTP) rule requirement for ultimate vertical bending moment capacity. The probability of structural failure is calculated using a 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 to IACS recommended procedure. Comparative analysis of long-term distributions of vertical wave bending moment calculated by two independent computer seakeeping codes is performed. 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 JTP single-step procedure and by program HULLCOLL for progressive collapse analysis of ship hull-girders. The reliability assessment is performed for “as-built” and “corroded” states of the existing ship and a reinforced design configuration complying with new JTP rules. It is shown that hull-girder failure probability of suezmax tanker reinforced according to new JTP rules is reduced several times. Sensitivity analysis and a parametric study are performed to investigate the variability of results to the change of parameters of pertinent random variables within their plausible ranges.

The application of Structural Reliability Analysis on hull girder ultimate strength of bulk carriers-a trial on Safety Level Approach

2015 ◽  
Author(s):  
Daokun Zhang ◽  
Wenyong Tang
Keyword(s):  
Reliability Analysis ◽  
Ultimate Strength ◽  
Structural Reliability ◽  
Safety Level ◽  
Hull Girder ◽  
Structural Rules ◽  
Structural Reliability Analysis ◽  
Trial Analysis ◽  
Bulk Carriers ◽  
Partial Safety Factors

The International Maritime Organization is developing the Goal Based Standard, in which the Safety Level Approach(SLA) is one of the two parallel ways forward focusing on deriving explicit and reasonable safety level. During the development of Safety Level Approach, the Structural Reliability Analysis(SRA) is recognized as one of the useful tools. The application of SRA on the calibration of partial safety factors for hull girder ultimate strength is so far a typical illustration, which could be very helpful for the application of Safety Level Approach on the structural Rules in the future. China Classification Society (CCS) carries out a trial analysis with co-operation of Shanghai Jiao Tong University.

Structural Reliability Analysis Applied on Steel Ships for Rule Partial Safety Factors Calibration

2017 ◽  
Author(s):  
Alexis Benhamou ◽  
Quentin Derbanne ◽  
Jérôme de Lauzon
Keyword(s):  
Reliability Analysis ◽  
Ultimate Strength ◽  
Structural Reliability ◽  
Bending Moment ◽  
Safety Factors ◽  
Structural Rules ◽  
Structural Reliability Analysis ◽  
Reliability Method ◽  
Partial Safety Factors ◽  
Common Structural Rules

Ultimate strength assessments in current IACS Common Structural Rules (CSR) are determined by a limited number of constant partial safety factors (PSF). These coefficients are inherited from the previous Common Structural Rules for Oil Tankers, and were determined using a structural reliability analysis (SRA) based on a limited number ship. The authors decided to lead a more comprehensive structural reliability analysis to propose and discuss a new set of rule formulations. A literature review is carried out in order to determine an extensive database of virtual ships covering the whole range of existing ships with a few representative parameters. SRA is applied for ultimate strength assessment on this database. Uncertainties are modeled by a set of probability distributions applied to each characteristic quantity (still water bending moment, wave bending moment and capacity) and a Second Order Reliability Method (SORM) is used to target the ultimate capacity corresponding to a given failure probability for each ship. A set of several PSF formulations are then derived from these results using both Working Stress Design (WSD) and Load and Resistance Factor Design (LRFD) approaches. These formulations are then discussed to get an optimum between simplicity and accuracy of the results.

scholarly journals Structural Reliability Assessment of an Oil Tanker Accidentally Grounded in the Adriatic Sea

2017 ◽  
Author(s):  
Maro Ćorak ◽  
Joško Parunov ◽  
C. Guedes Soares
Keyword(s):  
Structural Reliability ◽  
Adriatic Sea ◽  
Bending Moment ◽  
Sea State ◽  
Hull Girder ◽  
Increased Risk ◽  
Mc Simulation ◽  
Safety Indices ◽  
Oil Tanker ◽  
Rock Size

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.

scholarly journals Null modes effect in Rossby wave model

2004 ◽  
Vol 11 (3) ◽  
pp. 281-293
Author(s):  
V. Goncharov ◽  
V. Pavlov
Keyword(s):  
Nonlinear Wave ◽  
Rossby Wave ◽  
Wave Model ◽  
Wave Fields

Abstract. The problem of the null-modes existence and some particularities of their interaction with nonlinear vortex-wave-like structures is discussed. We show that the null-modes are fundamental elements of nonlinear wave fields. The conditions under which null-modes can manifest themselves are elucidated. The Rossby-Hasegawa-Mima (RHM) model is used for the illustration of features of null-modes-waves interactions.

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