Advanced Closed-Form Ultimate Strength Formulation for Ships

2001 ◽  
Vol 45 (02) ◽  
pp. 111-132 ◽  
Author(s):  
Jeom Kee Paik ◽  
Owen F. Hughes ◽  
Alaa E. Mansour
Keyword(s):  
Ultimate Strength ◽  
Structural Damage ◽  
Lateral Pressure ◽  
Local Buckling ◽  
Bending Moment ◽  
Stiffened Panels ◽  
Initial Imperfections ◽  
Ship Hulls ◽  
Collapse Column ◽  
Side Shell

The aim of this paper is to develop an advanced ultimate strength formulation for ship hulls under vertical bending moment. Since the overall failure of a ship hull is normally governed by buckling and plastic collapse of the deck, bottom, and sometimes the side shell stiffened panels, it is of crucial importance to accurately calculate the ultimate strength of stiffened panels in deck, bottom and side shell for more advanced ultimate strength analyses. In this regard, the developed formulation is designed to be more sophisticated than previous simplified theoretical methods for calculating the ultimate strength of stiffened panels under combined axial load, in-plane bending and lateral pressure. Fabrication-related initial imperfections (initial deflections and residual stresses) and potential structural damage related to corrosion, collision, or grounding are included in the panel ultimate strength calculations as parameters of influence. All possible collapse modes involved in collapse of stiffened panels, including overall buckling collapse, column or beam-column type collapse (plate or stiffener induced collapse), tripping of stiffeners and local buckling of stiffener web, are considered. As illustrative examples, the paper investigates and discusses the sensitivity of parameters such as lateral pressure, fabrication-related initial imperfections, corrosion, collision and grounding damage on the ultimate strength of a typical Cape size bulk carrier hull under vertical bending.

Advanced Ultimate Strength Formulations for Ship Plating Under Combined Biaxial Compression/Tension, Edge Shear, and Lateral Pressure Loads

2001 ◽  
Vol 38 (01) ◽  
pp. 9-25
Author(s):  
Jeom Kee Paik ◽  
Anil K. Thayamballi ◽  
Bong Ju Kim
Keyword(s):  
Ultimate Strength ◽  
Lateral Pressure ◽  
Limit State ◽  
Biaxial Compression ◽  
Ultimate Limit State ◽  
Initial Imperfections ◽  
Interaction Equation ◽  
Collapse Behavior ◽  
The Individual ◽  
Ultimate Limit

The aim of the present study is to develop more advanced design formulations for the ultimate strength of ship plating than available at present. Plate ultimate strength subject to any combination of the following four load components—longitudinal compression/tension, transverse compression/tension, edge shear, and lateral pressure loads—is addressed. The developed formulations are designed to be more sophisticated than existing theoretically based simplified methods. The influence of post-weld initial imperfections in the form of initial deflections and residual stresses is taken into account. It has been previously recognized that a single ultimate strength interaction equation cannot successfully represent the ultimate limit state of long and/or wide plating under all possible combinations of load components involved. This is due to the fact that the collapse behavior of the long and/or wide plating depends primarily on the predominant load components, implying that more than one strength interaction formulations may be needed to more properly predict the plate ultimate limit state. In this regard, the present study derives three sets of ultimate strength formulations for the long and/or wide plating under the corresponding primary load by treating lateral pressure as a secondary dead load. The ultimate strength interaction formula under all of the load components involved is then derived by a relevant combination of the individual strength formulas. The validity of the proposed ultimate strength equations is studied by comparison with nonlinear finite-element analyses and other numerically based solutions.

Ultimate Strength Analysis of Open Box Girders under Bending Moment and Lateral Pressure

2014 ◽  
Vol 578-579 ◽  
pp. 1571-1574
Author(s):  
Van Tan Vu ◽  
Wei Guo Wu
Keyword(s):  
Ultimate Strength ◽  
Lateral Pressure ◽  
Bending Moment ◽  
Nonlinear Finite Element ◽  
Strength Analysis ◽  
Nonlinear Finite Element Method ◽  
Bulk Carrier ◽  
Box Girders ◽  
Ship Model ◽  
Carrier Model

This paper made use of nonlinear finite element method to calculate the ultimate strength of bulk carrier model under bending moment and lateral pressure using a commercial FEA program, ABAQUS. It studies the ultimate strength bending moment of Nishihara bulk carrier model. This paper mainly analyzes the influence of the ultimate strength the bulk carrier model under bending moment and lateral pressure laying a foundation for accounting the ultimate strength of the actual ship model in next step.

Experimental Investigation of Residual Ultimate Strength of Damaged Metallic Pipelines

2017 ◽  
Author(s):  
Jie Cai ◽  
Xiaoli Jiang ◽  
Gabriel Lodewijks ◽  
Zhiyong Pei ◽  
Ling Zhu
Keyword(s):  
Ultimate Strength ◽  
Structural Damage ◽  
Large Scale ◽  
Bending Strength ◽  
Bending Moment ◽  
Tensile Tests ◽  
Metal Loss ◽  
Outer Diameter ◽  
Pipe Surface ◽  
Ultimate Bending Strength

The ultimate strength of metallic pipelines will be inevitably affected when they have suffered from structural damage. The present experiments aim to investigate the residual ultimate bending strength of metallic pipes with structural damage based on large-scale pipe specimens. Artificial damage such as dent, metal loss, crack and combinations thereof is introduced on the pipe surface in advance. The entire test project consists of 34 seamless pipes with a relative low Diameter-to-thickness (D/t) ratio around 21.3, among which four intact specimens and thirty damaged specimens have been carried out for mutual comparison. Extensive measurements on structural damage and pipe geometries including wall thickness and outer diameter are performed. The material properties are measured by tensile tests with specimens from both pipe longitudinal and hoop direction. The four-point bending tests are performed to investigate the structural behaviors of metallic pipes. The bending strength associating with failure mode of each specimen is documented extensively, and the bending moment-curvature curves are presented and discussed. The fundamental research of experiments on damaged pipes in the present paper will be deployed for the following numerical and analytical research in the near future.

Lateral Pressure Effects on the Ultimate Strength of Plates

2015 ◽  
Author(s):  
Lei Jiang ◽  
Shengming Zhang
Keyword(s):  
Ultimate Strength ◽  
Lateral Pressure ◽  
Numerical Study ◽  
Offshore Structures ◽  
Pressure Effects ◽  
Finite Element Program ◽  
Stiffened Panels ◽  
Element Program ◽  
Ocean Environment ◽  
Ultimate Load Carrying Capacity

During the operations of ships and offshore structures in the ocean environment, these structures are subjected to combined lateral pressure and in-plane stresses. However, in today’s ship design and analysis procedures, the effects of the lateral pressure on the ultimate strength of these structures are often ignored. Previous studies have indicated that the lateral pressure could have a noticeable influence on the ultimate load carrying capacity of stiffened panels when they are subjected to combined longitudinal and transverse stresses. The purpose of this paper is to present a systematic numerical study to quantify the lateral pressure effects on the ultimate strength of plates. The sensitivity of the plate’s ultimate strength to lateral pressure is characterized as a function of the plate geometry, the pressure magnitude and the ratio of the in-plane stress components. The present numerical study is performed by using LR’s in-house nonlinear finite element program VAST and the newly development LR procedure for nonlinear structural mechanics analysis was followed. The results and findings from this study are detailed in this paper.

Ultimate Strength and Effective Width Formulations for Ship Plating Subject to Combined Axial Load, Edge Shear, and Lateral Pressure

2000 ◽  
Vol 44 (04) ◽  
pp. 247-258 ◽  
Author(s):  
Jeom Kee Paik ◽  
Anil K. Thayamballi ◽  
Bong Ju Kim
Keyword(s):  
Closed Form ◽  
Ultimate Strength ◽  
Axial Load ◽  
Lateral Pressure ◽  
Plate Theory ◽  
Limit State ◽  
Ultimate Limit State ◽  
Effective Width ◽  
Ultimate Shear Strength ◽  
Initial Imperfections

The aim of the present study is to develop closed-form formulations for the ultimate strength of simply supported steel plating subject to a combination of longitudinal axial load, edge shear, and lateral pressure. The post-weld initial imperfections (initial deflections and residual stresses) are included in the strength formulations as parameters of influence. By solving the equilibrium and compatibility governing differential equations of large-deflection plate theory, the membrane stress distribution inside the plating under axial and lateral pressure loads is formulated in closed form. The ultimate strength formulation for plating under axial load and lateral pressure is then derived under the assumption that the ultimate limit state is reached if the plate edges yield. An empirical formula for the plate ultimate shear strength is suggested based on numerical FE solutions. A relevant ultimate strength relationship between axial load and edge shear is then proposed by combining the two sets of the ultimate strength formulations. As another contribution, the effective width formulation for plating under combined axial compression and edge shear which allows for the shear lag effect caused by lateral pressure as well as the influence of post-weld initial imperfections is developed. The validity of the proposed ultimate strength formulations is shown by comparing with experimental results and nonlinear finite-element analyses. Modeling uncertainty of the developed plate ultimate strength formula against the experimental and numerical results is studied in terms of bias and coefficients of variation.

Ultimate Strength of Stiffened Plates Subjected to Longitudinal Compression and Lateral Pressure

2014 ◽  
Author(s):  
Karan Doshi ◽  
Suhas Vhanmane
Keyword(s):  
Finite Element ◽  
Ultimate Strength ◽  
Lateral Pressure ◽  
Stiffened Plates ◽  
Stiffened Panel ◽  
Element Analysis ◽  
Stiffened Panels ◽  
Linear Finite Element ◽  
Non Linear ◽  
Compressive Loads

This paper presents a non-linear finite element analysis (FEA) and subsequent formula development for ultimate strength of stiffened panels of ship structures. A review of studies on ultimate strength of ship plating subjected to lateral pressure was carried out. The present work takes into account, the influence due to the lateral pressure on the ultimate strength of stiffened plates with initial imperfections subject to longitudinal compressive loads. ANSYS non-linear FE software was used for non linear finite element analyses of stiffened panels (864 cases) considering VLCC hull. Based on regression analysis, a set of semi-analytical formulae were proposed and described. It is observed that depending upon the failure mode, scantlings of the stiffened panel and magnitude of lateral pressure, ultimate strength of the stiffened panels in compression is affected.

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