Structural Reliability of Oil Tanker in the Adriatic Sea Damaged in Collision and Exposed to Combined Bending Moments

2019 ◽  
Vol 142 (3) ◽  
Author(s):  
Maro Ćorak ◽  
Joško Parunov
Keyword(s):  
Monte Carlo ◽  
Structural Reliability ◽  
Adriatic Sea ◽  
Regression Equations ◽  
Bending Moments ◽  
Load Combination ◽  
Horizontal Wave ◽  
Safety Indices ◽  
Oil Tanker ◽  
Damaged Ship

Abstract The aim of the paper is the assessment of structural reliability of oil tanker, damaged in collision accident in the Adriatic Sea and exposed to combined, horizontal, and vertical bending moments. Damage size is assumed based on the direct numerical simulation of the ship–ship collision. This is justified for some specific sea environments, as the Adriatic Sea, where ship sailing routes and representative ship types involved in accidents are known, so possible collision scenarios may be reasonably predicted. Residual bending moment capacity under combined bending moments (CBM) is calculated using regression equations developed based on non-linear finite element analysis. Still-water vertical bending moments are obtained by damage stability analysis for different collision scenarios that are generated by Monte Carlo (MC) simulations. Vertical and horizontal wave bending moments are determined by short-term response analysis of damaged ship in the Adriatic Sea, using transfer functions obtained by 3D panel hydrodynamic method. Monte Carlo time simulations are performed in order to study probabilistic load combination (LC) considering randomness of the wave process due to different phase angles. Limit state function is defined using interaction equation for damaged ship exposed to combined bending moments. Safety indices are calculated by FORM for each damage scenario by using Turkstra's rule for load combination of vertical and horizontal wave bending moments. Such an approach enables to determine the safety indices for the most frequent damages and also to reveal the most critical situations resulting in the lowest safety indices.

Structural Reliability of Oil Tanker in the Adriatic Sea Damaged in Collision and Exposed to Combined Bending Moments

2018 ◽  
Author(s):  
Maro Ćorak ◽  
Joško Parunov
Keyword(s):  
Structural Reliability ◽  
Adriatic Sea ◽  
Bending Moment ◽  
State Function ◽  
Regression Equations ◽  
Bending Moments ◽  
Damage Stability ◽  
Safety Indices ◽  
Oil Tanker ◽  
Damaged Ship

The aim of the paper is the assessment of structural reliability of oil tanker which may be damaged in collision accident in the Adriatic Sea and exposed to combined, horizontal and vertical bending moments. Damage size is assumed based on the direct numerical simulation of the ship-ship collision. This is justified for some specific sea environments, as the Adriatic Sea, where ship sailing routes and representative ship types involved in accidents are known, so possible collision scenarios may be reasonably predicted. Residual bending moment capacity under combined bending moment is calculated using regression equations developed based on non-linear finite element analysis. Still water vertical bending moments are obtained by damage stability analysis. Vertical and horizontal wave bending moments are determined by short-term response analysis of damaged ship in the Adriatic Sea, using transfer functions obtained by 3D panel hydrodynamic method. Limit state function is defined using interaction equation for damaged ship exposed to combined bending moments. Safety indices are calculated by FORM for different collision scenarios that are generated by MC simulations. Such approach enables to determine the safety indices for the most frequent damages and also to reveal the most critical situations resulting in the lowest safety indices.

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.

Probabilistic Load Combination Factors of Wave and Whipping Bending Moments

2015 ◽  
Vol 59 (01) ◽  
pp. 11-30
Author(s):  
Maro Corak ◽  
Joško Parunov ◽  
C. Guedes Soares
Keyword(s):  
Extreme Values ◽  
Bending Moment ◽  
Practical Method ◽  
Time Instant ◽  
Regression Equations ◽  
Bending Moments ◽  
Short Term ◽  
Load Combination ◽  
Combination Methods ◽  
Probabilistic Load

Extreme values of wave and whipping bending moments are important in structural design of large containerships. Since the extreme values of these two, partially correlated processes do not occur at the same time instant and even at the same environmental conditions, it is necessary to combine them by using probabilistic load combination methods. The correlation analysis between wave and whipping bending moments is performed and a practical method for calculation of the most probable load combination factor between considered bending moments is presented. Short-term load combination factors are calculated by reconstruction of the signal from the frequency domain solution. Results are validated by comparison with model test data of the 9400-TEU containership for various sea states and speeds and heading angles. Practical regression equations for estimation of the most probable short-term load combination factor are formulated. Regression equations are then used in the computation of the long-term distribution of combined bending moment. The procedure is demonstrated on the example of the two large containerships.

The Effect of Sloshing in Tanks on the Hull Girder Bending Moments and Structural Reliability of Damaged Vessels

2012 ◽  
Vol 56 (01) ◽  
pp. 48-62
Author(s):  
Huirong Jia ◽  
Torgeir Moan
Keyword(s):  
Failure Probability ◽  
Structural Reliability ◽  
Bending Moments ◽  
Multimodal Approach ◽  
Coupled Motion ◽  
Rectangular Shape ◽  
Hull Girder ◽  
Set Up ◽  
Oil Tanker ◽  
Damaged Vessel

The structural reliability analysis of damaged vessels has commonly been conducted by neglecting the effect of sloshing. In this paper, the coupled motion of the damaged vessel and sloshing is set up based on the assumption that the damaged tanks are of rectangular shape. The sloshing effects in tanks are modeled by a linear multimodal approach. Then the effect of sloshing in tanks on the hull girder bending moments and the failure probability are studied for an oil tanker in various damage conditions. It is concluded that in certain tank resonance conditions, sloshing effects cannot be neglected. In such cases sloshing damping plays an important role on the sloshing effects.

RISK ANALYSIS OF OFFSHORE TRANSPORTATION ACCIDENT IN ARCTIC WATERS

2021 ◽  
Vol 159 (A3) ◽  
Author(s):  
R Abbassi ◽  
F Khan ◽  
N Khakzad ◽  
B Veitch ◽  
S Ehlers
Keyword(s):  
Monte Carlo ◽  
Risk Analysis ◽  
Historical Data ◽  
Fault Trees ◽  
Northern Sea Route ◽  
Accident Scenarios ◽  
Oil Tanker ◽  
Harsh Conditions ◽  
Monte Carlo Framework ◽  
Transportation Accident

A methodology for risk analysis applicable to shipping in arctic waters is introduced. This methodology uses the Bowtie relationship to represent an accident causes and consequences. It is further used to quantify the probability of a ship accident and also the related accident consequences during navigation in arctic waters. Detailed fault trees for three possible ship accident scenarios in arctic transits are developed and represented as bowties. Factors related to cold and harsh conditions and their effects on grounding, foundering, and collision are considered as part of this study. To illustrate the application of the methodology, it is applied to a case of an oil-tanker navigating on the Northern Sea Route (NSR). The methodology is implemented in a Markov Chain Monte Carlo framework to assess the uncertainties arisen from historical data and expert judgments involved in the risk analysis.

Load Combination for Fatigue Analysis of Ship Structures

2004 ◽  
Author(s):  
Yung S. Shin ◽  
Booki Kim ◽  
Alexander J. Fyfe
Keyword(s):  
Bending Moment ◽  
Linear Summation ◽  
Load Combination ◽  
Longitudinal Stiffeners ◽  
Stress Components ◽  
Tank Pressure ◽  
Wave Induced ◽  
Vertical Bending Moment ◽  
Oil Tanker

A methodology for calculating the correlation factors to combine the long-term dynamic stress components of ship structure from various loads in seas is presented. The methodology is based on a theory of a stationary ergodic narrow-banded Gaussian process. The total combined stress in short-tem sea states is expressed by linear summation of the component stresses with the corresponding combination factors. This expression is proven to be mathematically exact when applied to a single random sea. The long-term total stress is similarly expressed by linear summation of component stresses with appropriate combination factors. The stress components considered here are due to wave-induced vertical bending moment, wave-induced horizontal bending moment, external wave pressure and internal tank pressure. For application, the stress combination factors are calculated for longitudinal stiffeners in cargo and ballast tanks of a crude oil tanker at midship section. It is found that the combination factors strongly depend on wave heading and period in the short-term sea states. It is also found that the combination factors are not sensitive to the selected probability of exceedance level of the stress in the long-term sense.

IMPERFECTION SENSITIVITY AND RELIABILITY USING SIMPLE BAR-SPRING MODELS FOR STABILITY

2013 ◽  
Vol 13 (03) ◽  
pp. 1250075 ◽  
Author(s):  
VAHID ZEINODDINI MEIMAND ◽  
LORI GRAHAM-BRADY ◽  
BENJAMIN WILLIAM SCHAFER
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Ultimate Strength ◽  
Structural Reliability ◽  
Plastic Hinge ◽  
Continuous Systems ◽  
Plastic Collapse ◽  
Imperfection Sensitivity ◽  
Element Analysis ◽  
First Order

The objective of this paper is to demonstrate how simple bar-spring models can illustrate elementary and advanced structural behavior, including stability, imperfection sensitivity, and plastic collapse. In addition, the same bar-spring models also provide a ready means for assessing structural reliability. Bar-spring models for a column (both post-buckling stable and unstable), a frame, and a plate are all developed. For each model the influence of geometric imperfections are explicitly introduced and the ultimate strength considering plastic collapse of the supporting springs derived. The developed expressions are compared to material and geometric nonlinear finite element analysis models of analogous continuous systems, using yield surface based plastic hinge beam elements (in MASTAN) for the column and frame and shell elements (in ABAQUS) for the plate. The results show excellent qualitative agreement, and surprisingly good quantitative agreement. The developed bar-spring models are used in Monte Carlo simulations and in the development of first order Taylor Series approximations to provide the statistics of the ultimate strength as used in structural reliability calculations. Good agreement between conventional first order second moment assumptions and the Monte Carlo simulations of the bar-spring models is demonstrated. It is intended that the developed models provide a useful illustration of basic concepts central to structural stability and structural reliability.

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