Ultimate strength of a box girder simulating the hull of a ship

1998 ◽  
Vol 25 (5) ◽  
pp. 829-843 ◽  
Author(s):  
Georges Akhras ◽  
Stephen Gibson ◽  
Stephen Yang ◽  
Richard Morchat
Keyword(s):  
Residual Stresses ◽  
Ultimate Strength ◽  
Experimental Results ◽  
Structural Behaviour ◽  
Pure Bending ◽  
Box Girder ◽  
Initial Imperfections ◽  
Construction Methods ◽  
Geometrical Imperfections ◽  
Computer Codes

An important feature of ship design is the ability to describe the structural behaviour of the hull and to accurately predict its ultimate strength. Research on the ultimate strength of hulls has been carried out by many experimental research groups. Recently, the consensus reached is to simulate the behaviour of the hull by loading a box girder up to its ultimate strength. A box girder was tested at the Royal Military College of Canada. The objective of this experiment is to study the structural behaviour and compare the experimental results with the predictions of two computer codes. The construction of the model follows typical hull construction methods. The girder was subjected to pure bending until failure occurred. Provisions were taken so that collapse would occur due to buckling and not to plastic failure. Residual stresses and initial geometrical imperfections were measured and considered in the analysis. In previous publications, details of the design, fabrication, and loading were presented. In this paper, the experimental results are described and discussed.Key words: box girder, ship's hull, bending, ultimate strength, residual strength, residual stresses, initial imperfections.

scholarly journals Experimental and Numerical Investigations of Ultimate Strength of Imperfect Stiffened Plates of Different Slenderness

2020 ◽  
Vol 27 (4) ◽  
pp. 120-129
Author(s):  
Krzysztof Woloszyk ◽  
Yordan Garbatov ◽  
Jakub Kowalski ◽  
Leszek Samson
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Ultimate Strength ◽  
Compressive Force ◽  
Initial Imperfection ◽  
Element Model ◽  
Stiffened Plates ◽  
Structural Behaviour ◽  
Middle Cross Section ◽  
Geometrical Imperfections

AbstractThe objective of this study is to analyse the behaviour of compressed stiffened plates of different slenderness using experimental and numerical methods. The presented results are part of a long-term project to investigate the ultimate strength of geometrically imperfect structures subjected to different degradation phenomena, including corrosion degradation and locked cracks. Several specimens were subjected to a uniaxial compressive force, and the most important quantities related to the structural behaviour were captured and analysed. A finite element model, accounting for material and geometrical nonlinearities and initial geometrical imperfections, was developed using the commercial software ANSYS. The residual welding-induced stresses were measured in the middle cross-section for two specimens. The initial imperfection was identified by employing a close-range photogrammetry approach. It was concluded that the numerical analyses, based on the finite element model, predict the ultimate strength of stiffened plates accurately, although some deviations were also observed. The detailed analysis with the indication of possible uncertainty is presented, and several conclusions are derived.

Buckling and Post Buckling Behavior of a Transversely Stiffened Ship Hull Model

1964 ◽  
Vol 8 (04) ◽  
pp. 7-21
Author(s):  
H.G. Schultz
Keyword(s):  
Reasonable Agreement ◽  
Ship Hull ◽  
Buckling Load ◽  
Experimental Results ◽  
Postbuckling Behavior ◽  
Pure Bending ◽  
Box Girder ◽  
Buckling Behavior ◽  
Theoretical Investigations ◽  
Post Buckling

In the paper presented the behavior of a transversely formed box-girder model subjected to pure bending is discussed, where the deck plating of the model is loaded above the buckling load. The experimental results obtained are in reasonable agreement with theoretical investigations and show the influence of fabrication initiated plate deflections on the buckling and postbuckling behavior of the deck plating clearly. A method is suggested for determining the buckling load of plates having large initial deformations.

An Analysis of the Ultimate Strength of Deck Structures Under In-Plane Loads

1983 ◽  
Vol 20 (03) ◽  
pp. 230-251
Author(s):  
Ygal Shapir ◽  
Gregory J. White
Keyword(s):  
Residual Stresses ◽  
Ultimate Strength ◽  
Experimental Results ◽  
Correction Factors ◽  
Buckling Strength ◽  
Step Procedure ◽  
Simple Program ◽  
Mode Of Failure ◽  
Compressive Loads ◽  
Simple Flow

A step-by-step procedure for determining the mode of failure and the ultimate strength of ship deck structures under in-plane compressive loads is developed. A comparison of several analytical theories for the buckling strength of deck structures in the elastic and inelastic zones is presented and the reason for the approach taken at each step is explained. The final result is a simple flow chart for this procedure and an algorithm which is easily adapted to most computer systems. The procedure is compared with experimental results and a method for determining reasonable size factors of safety (or correction factors) to account for initial deflections, residual stresses, etc., is presented. An example coding in FORTRAN IV for use as a subroutine in larger programs, or as a simple program itself, is given. An example structure is solved to explain each of the steps of the procedure.

Full-Scale Measurements of Welding-Induced Initial Deflections and Residual Stresses in Steel-Stiffened Plate Structures

2018 ◽  
Vol Vol 160 (A4) ◽  
Author(s):  
M S Yi ◽  
C M Hyun ◽  
J K Paik
Keyword(s):  
Residual Stresses ◽  
Ultimate Strength ◽  
Computational Models ◽  
Plate Thickness ◽  
Offshore Structures ◽  
Full Scale ◽  
Stiffened Plate ◽  
Plate Structures ◽  
Initial Imperfections ◽  
Numerical Predictions

Plated structures such as ships and offshore structures are constructed using welding techniques that attach support members (or stiffeners) to the plating. During this process, initial imperfections develop in the form of initial deformations (deflections or distortions) and residual stresses. These initial imperfections significantly affect the buckling and ultimate strength of these structures. Therefore, to assess the strength of welded plate structures, it is very important to predict the magnitude and pattern of welding-induced initial imperfections and their effects on buckling and ultimate strength. To determine the reliability of the prediction methods, it is desirable to validate the theoretical or numerical predictions of welding-induced initial imperfections through comparison with full-scale actual measurements. However, full-scale measurement databases are lacking, as they are costly to obtain. This study contributes to the development of a full-scale measurement database of welding-induced initial imperfections in steel-stiffened plate structures. The target structures are parts of real (full-scale) deckhouses in very large crude oil carrier class floating, production, storage and offloading unit structures. For parametric study purposes, four test structures by varying plate thickness are measured while the stiffener types and weld bead length are fixed. Modern technologies for measuring initial deformations and residual stresses are applied. The details of the measurement methods are documented for the use of other researchers and practicing engineers who want to validate their computational models for predicting welding-induced initial imperfections.

Experimental Determination of the Ultimate Strength of Box Girder Specimens

2016 ◽  
Author(s):  
Thomas Lindemann ◽  
Patrick Kaeding ◽  
Eldor Backhaus
Keyword(s):  
Finite Element ◽  
Experimental Determination ◽  
Ultimate Strength ◽  
Progressive Collapse ◽  
Bending Moment ◽  
Element Model ◽  
Experimental Results ◽  
Bending Test ◽  
Box Girder

The Finite Element Method (FEM) is a feasible tool to perform progressive collapse analyses of large structural systems. Despite enormous developments in finite element formulations and computer technologies the results of structural analyses should be validated against experimental results. In this paper the collapse behaviour of two identical box girder specimens is determined experimentally for the load case of pure longitudinal bending. The specimens are composed of stiffened plate panels and connected at either ends to a loading structure. Within a 4-point bending test a constant bending moment is applied to each specimen to determine the collapse behaviour even in the post-ultimate strength range. The results of the experimental determination of the ultimate strength are presented for the box girder specimens. To simulate the collapse behaviour a finite element model is used and validated against experimental results.

Corrosion-Dependent Ultimate Strength Assessment of Aged Box Girders Based on Experimental Results

2011 ◽  
Vol 55 (04) ◽  
pp. 289-300 ◽  
Author(s):  
S. Saad-Eldeen ◽  
Y. Garbatov ◽  
C. Guedes Soares
Keyword(s):  
Service Life ◽  
Residual Stresses ◽  
Ultimate Strength ◽  
Bending Moment ◽  
Experimental Results ◽  
Time Dependent ◽  
Strength Analysis ◽  
Box Girders ◽  
Strength Assessment ◽  
Equivalent Time

This paper presents a corrosion-dependent analysis of the ultimate strength analysis of aged box girders based on experimental results. Three multispan corroded stiffened box girders subjected to four-point vertical load are analyzed, idealizing the behavior of midship sections of full ships. The specimens have three levels of corrosion. Two corrosion-dependent formulas for assessing the ultimate strength as well as the ultimate bending moment of corroded structures are proposed. Using a time-dependent corrosion growth model, equivalent time-dependent formulations are developed. The effect of corrosion degradation on the residual stresses during the service life is also analyzed, and a regression equation for predicting the remaining residual stresses along the service life is proposed. Finally, a corrosion-dependent moment-curvature relationship has been developed accounting for the changes in geometrical characteristics and material properties of the tested box girders.

The Effect of Bottom Damage Size of Stranded Ship on Ultimate Strength

2008 ◽  
Author(s):  
Chae Whan Rim ◽  
Tak Kee Lee ◽  
Dae Suk Han ◽  
Byung Hyun Kim ◽  
Jae Myung Lee ◽  
...  
Keyword(s):  
Ultimate Strength ◽  
Applied Load ◽  
Estimation Method ◽  
Pure Bending ◽  
Box Girder ◽  
Ship Structure ◽  
Damage Area ◽  
Hull Structure ◽  
Bending Load ◽  
Rock Section

Ships operating in littoral sea are likely to be subjected to accidental loads especially stranding. Once she has damage on the hull structure, her ultimate strength will be reduced. This paper is to investigate the effect of stranding damage size on the ultimate strength of ship structure by using a series of collapse tests. For the experiment, five box-girder models of 720mm × 720mm in section and 900mm in length were prepared. Of the five, one has no damage and each four have a diamond shaped damage of different size which represents the shape of rock section in seabed. Among the damaged models, three were made by cutting the plate and one by pressing to represent stranding damage. Experiments were carried out under pure bending load and the applied load and displacements were recorded. The ultimate strength is reduced as the damage size increases, as expected. The largest damaged model has the damage size of 30% of breadth and its ultimate strength is reduced by 21% than that of no damaged one. The pressed one has lower ultimate strength than cut one. This might be due to the fact that the plate around the pressed damage area effect unfavorably on the ultimate strength. The models are analyzed with LS-DYNA and the results are compared with the results from the experiments. From the intact model, buckling occurred in the analysis but not in the experiment. The ultimate strengths of other models from the analysis are fairly close to those from the experiments. The errors are within 10%. With the results from the experiments and analysis, an estimation method of ultimate strength of damaged ship on bottom is derived.

FULL-SCALE MEASUREMENTS OF WELDING-INDUCED INITIAL DEFLECTIONS AND RESIDUAL STRESSES IN STEEL-STIFFENED PLATE STRUCTURES

2021 ◽  
Vol 160 (A4) ◽  
Author(s):  
M S Yi ◽  
C M Hyun ◽  
J K Paik
Keyword(s):  
Residual Stresses ◽  
Ultimate Strength ◽  
Plate Thickness ◽  
Offshore Structures ◽  
Full Scale ◽  
Stiffened Plate ◽  
Plate Structures ◽  
Initial Imperfections ◽  
Numerical Predictions ◽  
Modern Technologies

Plated structures such as ships and offshore structures are constructed using welding techniques that attach support members (or stiffeners) to the plating. During this process, initial imperfections develop in the form of initial deformations (deflections or distortions) and residual stresses. These initial imperfections significantly affect the buckling and ultimate strength of these structures. Therefore, to assess the strength of welded plate structures, it is very important to predict the magnitude and pattern of welding-induced initial imperfections and their effects on buckling and ultimate strength. To determine the reliability of the prediction methods, it is desirable to validate the theoretical or numerical predictions of welding-induced initial imperfections through comparison with full-scale actual measurements. However, full-scale measurement databases are lacking, as they are costly to obtain. This study contributes to the development of a full-scale measurement database of welding-induced initial imperfections in steel-stiffened plate structures. The target structures are parts of real (full-scale) deckhouses in very large crude oil carrier class floating, production, storage and offloading unit structures. For parametric study purposes, four test structures by varying plate thickness are measured while the stiffener types and weld bead length are fixed. Modern technologies for measuring initial deformations and residual stresses are applied. The details of the measurement methods are documented for the use of other researchers and practicing engineers who welding-induced initial imperfections.

Reliability-Based Allowable Unfairness Tolerances for Unstiffened Plates

1999 ◽  
Vol 43 (04) ◽  
pp. 255-265
Author(s):  
Alaa Mansour ◽  
Tarek Elsayed
Keyword(s):  
Residual Stresses ◽  
Ultimate Strength ◽  
Simple Formula ◽  
Slenderness Ratio ◽  
Reliability Assessment ◽  
Simple Expression ◽  
Ship Structures ◽  
Initial Imperfections ◽  
Strength Failure

A procedure and a simple formula have been developed for determining the maximum allowable plating unfairness tolerance in ship panels. The formula is based on reliability assessment of strength of unstiffened plates having initial imperfections. Plate ultimate strength is determined by taking into account the effects of initial deflections and residual stresses. A series of plate reliability analyses relative to the ultimate strength failure, for varying plate unfairness, and aspect and slenderness ratios, is carried out. Based on the computed results, a simple expression for predicting the maximum allowable unfairness tolerance of the plate is derived. The developed expression, described in terms of the plate slenderness ratio, can be useful for the assessment of unfairness limits of plating between frames in ship structures.

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