• Journal of Ship and Ocean Technology
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• v.8 no.4
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• pp.17-25
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• 2004

Hull girder stress monitoring system for container ship uses four long-base-strain-gages at mid-ship to monitor the resultant stresses and the applied moment components of horizontal, vertical and torsional moments. The bending moments are estimated by using the conventional strain-moment relations, however, the torsional moment related to the warping strain requires the assumption of the shape of torsional moments over the hull girder. Though this shape could be a sine function with an adequate period, it largely depends upon certain empirical formulas. This paper introduces additional four long-base-strain-gages at mid-ship to derive the longitudinal slope of the warping strain because this slope is directly related to the torsional moment by Bi-moment concept. An open-channel-type cantilever beam has been selected as a simplified model for container ship and the result has proved that the suggested concepts can estimate the torsional component accurately. Finally this method can become reliable technique to derive all external moments in hull girder stress monitoring system for container ships.

• Journal of Ship and Ocean Technology
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• v.7 no.3
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• pp.56-65
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• 2003

The hull monitoring systems of container ships with four long-base gages give enough information for identifying the hull girder loads such as bending and torsional moments. But such a load-identification for container ships has not been known. In this paper, a load-identification method is suggested in terms of a linear matrix equation that the measured strain vector equals to the multiplication of the transformation matrix and the desired strain component vector. The equation is proved to be mathematically complete by the property of positive-definite determinant of the transformation matrix. The method is applied to a hull stress monitoring system for 8100TED container ship during sea trial, and the estimated external loads illustrate reasonable results in comparison with the pre-estimated results. This moment decomposition concept has also been tested in real operation conditions. The typical phenomena over the Suez Canal illustrated very suitable results comparing with the physical understandings. Henceforth, one can effectively use the proposed concept to monitor the hull girder loads such as bending and torsional moments.

• Structural Engineering and Mechanics
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• v.42 no.4
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• pp.531-549
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• 2012

Numerous oil tanker losses have been reported and one of the possible causes of such casualties is caused by the structural failure of aging ship hulls in rough weather. In aging ships, corrosion and fatigue cracks are the two most important factors affecting structural safety and integrity. This research is about effect on hull girder ultimate strength behavior of double hull oil tanker according to corrosion after Part I: stiffened panel. Based on corrosion data of Part I (time-dependent corrosion wastage model and CSR corrosion model), when progressing corrosion of fourtypes of double hull oil tankers (VLCC, Suezmax, Aframax, and Panamax), the ultimate strength behavior of hull girder is compared and analyzed. In case of the ultimate strength behavior of hull girder, when occurring corrosion, the result under vertical and horizontal bending moment is analyzed. The effect of time-dependent corrosion wastage on the ultimate hull girder strength as well as the area, section modulus, and moment of inertia are also studied. The result of this research will be useful data to evaluate ultimate hull girder strength of corroded double hull oil tanker.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.1
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• pp.21-36
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• 2018

The incidence of collision damage models on oil tanker and bulk carrier reliability is investigated considering the IACS deterministic model against GOALDS/IMO database statistics for collision events, substantiating the probabilistic model. Statistical properties of hull girder residual strength are determined by Monte Carlo simulation, based on random generation of damage dimensions and a modified form of incremental-iterative method, to account for neutral axis rotation and equilibrium of horizontal bending moment, due to cross-section asymmetry after collision events. Reliability analysis is performed, to investigate the incidence of collision penetration depth and height statistical properties on hull girder sagging/hogging failure probabilities. Besides, the incidence of corrosion on hull girder residual strength and reliability is also discussed, focussing on gross, hull girder net and local net scantlings, respectively. The ISSC double hull oil tanker and single side bulk carrier, assumed as test cases in the ISSC 2012 report, are taken as reference ships.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.902-909
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• 2020

It is announced a new procedure for the real-time overall hull response monitoring system depends on inclinometer sensor data. The procedure requires a few inclinometer sensors' data, located on the deck. Sensor data is used to obtain curvature values; and curvature values are used to find out displacements or relevant moment values according to pre-calculated moment-curvature diagrams. Numerical studies are demonstrated with reasonable accuracy for the pre-ultimate and the post-ultimate nonlinear behaviors. Elastic, inelastic, and post-collapse structural bending moment capacity determination of the hull has been presented. The proposed inverse engineering technique will be able to see the response of the hull in real-time with high accuracy to manage the course and speed when cruising or control the loading and the unloading process at the port.

• Journal of Ocean Engineering and Technology
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• v.25 no.3
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• pp.1-10
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• 2011

This paper estimates the residual longitudinal strength of a damaged double hull VLCC (Very Large Crude Carrier) under combined vertical and horizontal bending moments using Smith's method. The damage estimated in this study occurred due to collision or grounding accidents. The effects of the randomness of the yield stress, plate thickness, extent of damage, and the combination of these three parameters on the ultimate hull girder strength were investigated. Random variables were generated by a Monte Carlo simulation and applied to the double hull VLCC described by the ISSC (International Ship and Offshore Structures Congress) 2000 report.

• Journal of Ocean Engineering and Technology
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• v.6 no.2
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• pp.103-112
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• 1992

The calculation method which takes into account the shear lag effects on the ultimate transverse bending moment of a SWATH(Small Waterplane Area Twin Hull) ship has been developed. In case of the ultimate bending strength analysis of conventional monohull ships and general box girder structures, the hypothesis that plane section remains plane after bending can be employed but not in the case of the structures having wide flange. For the ultimate bending strength analysis of such structures, a new method which can take into account the effect of shear lag on the ultimate bending strength has been developed by adopting more reasonable assumption that warping distortion of the section takes place inthe same way as the actual stress distribution. Finally, the proposed method has been applied to a a SWATH cross deck structure.

• Journal of Navigation and Port Research
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• v.31 no.3 s.119
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• pp.235-245
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• 2007

Stiffened steel plates are basic structural members on the deck and bottom structure in ship, offshore. It has a number of one sided stiffeners in either one or both directions, the latter structure was called grillage structure. At the ship structural desgn stage, one of the major consideration is evaluation for ultimate strength of the hull girder. In general, it is accepted that hull girder strength can be represented by the local strength of the longitudinal stiffened panel. In case of considering hogging condition in a stormy sea, stiffened panel was acting on the bottom structure under axial compressive load induced hull girder bending moment, also simultaneously arising local bending moment induced lateral pressure load. In this paper, results of the structural analysis have been compared with another detailed FEA program and prediction from design guideline and a series analysis was conducted consideration of changing parameters for instance, analysis range, cross-section of stiffener, web height and amplitude of lateral pressure load subjected to combined load (axial compression and lateral pressure load). It has been found that finite element modeling is capable of predicting the behaviour and ultimate load capacity of a simply supported stiffened plate subjected to combined load of axial compression and lateral pressure load It is expected that these results will be used to examine the effect of interaction between lateral pressure and axial loads for the ultimate load-carrying capacity based on the Ultimate Limit State design guideline.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.58-58
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• 2010

The purpose of this study is to evaluate the structural safety at the topside weldment of hull structure, which was welded after launching. For it, the variations of residual stress and distortion at the topside weldment with loading conditions such as hull girder hogging bending moment after launching and free initial loading state was evaluated by using FEA. And the maximum stress range at the weldment under design loads specified by classification society was evaluated by FEA. In this case, the residual stress and welding distortion at the topside weldment was assumed to be initial imperfection. In accordance with FEA results, regardless of initial loading condition, tensile residual stress was found. However, the residual stress and welding distortion at the topside weldment produced under hogging condition was less than those of topside weldment under free loading state. That is, the amount of residual stress at the topside weldment decreased with an increase in the amount of tension load caused by hogging condition. It was because the compressive thermal strain at the topside weldment produced during welding was reduced by tensile load. However, the maximum stress range at the topside weldment under maximum hull girder bending moment was almost similar regardless of initial loading condition. So, if the problem related to the soundness of weldment is not introduced by initial load, the effect of initial loading condition during welding on fatigue strength of topside weldment could be negligible.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.21 no.1
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• pp.67-74
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• 1985

This paper describes a method for evaluating the vertical hull girder vibratory response associated with slamming of a ship at sea. The ship hull is considered as a nonuniform beam divided into twenty equal sections. Impact forces and structural parameters are used as input quantities on the computer (PRIME 550-II) to obtain the hull girder response in terms of relative displacements, accelerations, bending moments, shear forces, and stresses. Sample calculations are made on a MARINER-Class hull form using first three modes and again using first ten modes and again using first ten modes. The computed response is compared with Antonides's result in order to evaluate the adequacy of the method employed. It is believed that the method is another noticeable one to obtain whipping stresses of a ship to a seaway.