The Reliability Of Watertight Longitudinal Girders Of Fuel Tanks On Aging Bulk Carriers

2021 ◽  
Vol 93 (6s) ◽  
pp. 175-185
Author(s):  
Špiro Ivošević ◽  
◽  
Nataša Kovač ◽  
Keyword(s):  
Plate Thickness ◽  
Steel Plates ◽  
Structural Elements ◽  
Operational Conditions ◽  
Metal Plates ◽  
Bulk Carriers ◽  
Fuel Tanks ◽  
Failure Intensity ◽  
Longitudinal Strength ◽  
The Stability

During the exploitation of bulk carriers, the condition of structural elements and areas depends on the type of the cargo transported, operational conditions and maintenance systems. Corrosion significantly accelerates the aging of metal plates and girders thus causing the deterioration of steel surfaces, which consequently reduces the reliability of structural elements, areas and ships in general. The damage to metal structures can impair the stability of a ship, reduce longitudinal strength, cause the ingress of water into the hull as well as environmental pollution through fuel spills from the tanks. Therefore, the paper analyzes a part of a double bottom structure based on the available wear data on watertight longitudinal girders of fuel tanks. The research included 25 bulk carriers aged between 5 and 25 with the total of 110 fuel tanks. The reliability analysis of steel plates included the total of 1920 data measured. The allowable wear of structural plate thickness that equals 20% of the original thickness value was determined by the application of the acceptance criteria that were prescribed by classification societies. The calculations of the function of failure density, failure intensity and reliability determined the time when the condition of structural elements deteriorates due to corrosion up to the levels that require extensive maintenance services.

scholarly journals Stability charts based on the finite element method for underground cavities in soft carbonate rocks: validation through case-study applications

2019 ◽  
Vol 19 (10) ◽  
pp. 2079-2095 ◽  
Author(s):  
Michele Perrotti ◽  
Piernicola Lollino ◽  
Nunzio Luciano Fazio ◽  
Mario Parise
Keyword(s):  
Finite Element ◽  
Safety Margin ◽  
Structural Elements ◽  
The Finite Element Method ◽  
Geometrical Features ◽  
Overall Stability ◽  
Underground Cavities ◽  
The Stability ◽  
Rock Mechanical Properties

Abstract. The stability of man-made underground cavities in soft rocks interacting with overlying structures and infrastructures represents a challenging problem to be faced. Based upon the results of a large number of parametric two-dimensional (2-D) finite-element analyses of ideal cases of underground cavities, accounting for the variability both cave geometrical features and rock mechanical properties, specific charts have been recently proposed in the literature to assess at a preliminary stage the stability of the cavities. The purpose of the present paper is to validate the efficacy of the stability charts through the application to several case studies of underground cavities, considering both quarries collapsed in the past and quarries still stable. The stability graphs proposed by Perrotti et al. (2018) can be useful to evaluate, in a preliminary way, a safety margin for cavities that have not reached failure and to detect indications of predisposition to local or general instability phenomena. Alternatively, for sinkholes that already occurred, the graphs may be useful in identifying the conditions that led to the collapse, highlighting the importance of some structural elements (as pillars and internal walls) on the overall stability of the quarry system.

Effect of Detailed Formations on the In-Plane Shear Capacity of Hairpin Connectors in Precast RC Floor Slabs

2010 ◽  
Vol 163-167 ◽  
pp. 1510-1514 ◽  
Author(s):  
Rui Pang ◽  
Shu Ting Liang ◽  
Xiao Jun Zhu ◽  
Yao Meng
Keyword(s):  
Simulation Analysis ◽  
Plate Thickness ◽  
Shear Capacity ◽  
Steel Plates ◽  
Strong Impact ◽  
Deformation Capacity ◽  
Initial Stiffness ◽  
Plane Shear ◽  
Floor Slabs ◽  
Strength And Deformation

Detailed formation of precast floor slab connectors has significant effect on their shear capacity, but there is no such specific provision on it at present. The effects of detailed formations on the shear strength, stiffness and deformation capacity of hairpin connectors(HPC) were studied, through numerical simulation analysis under in-plane shear force. The imbedded depth (d), slug length (h), steel plate thickness (t) and its stickout(s) were taken as parameters. The analysis results show that: ⅰ) the increase of imbedded depth can improve the bearing capacity and stiffness of HPC, but decrease the deformation capacity; ⅱ) with the increase of slug length, the HPC strength, stiffness and deformation capacity raised a lot; ⅲ) the steel plates’ thickness has small effect on the stiffness, but has strong impact on the strength and deformation capacity of HPC. ⅳ) the stickout can affect the initial stiffness and yield strength of HPC slightly, but has a considerable impact on its ultimate strength and deformation capacity. On the basis of analysis, recommendations on formation details of HPC are proposed for design and construction.

Flexural bearing capacity of RC hollow slab beam strengthened by steel plates of different thicknesses

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Long Liu ◽  
Lifeng Wang ◽  
Ziwang Xiao
Keyword(s):  
Finite Element ◽  
Bearing Capacity ◽  
Steel Plate ◽  
Plate Thickness ◽  
Research Field ◽  
Steel Plates ◽  
Nonlinear Material ◽  
Finite Element Models ◽  
Content Type ◽  
Flexural Bearing Capacity

PurposeThe flexural reinforcement of bridges in-service has been an important research field for a long time. Anchoring steel plate at the bottom of beam is a simple and effective method to improve its bearing capacity. The purpose of this paper is to explore the influence of anchoring steel plates of different thicknesses on the bearing capacity of hollow slab beam and to judge its working status.Design/methodology/approachFirst, static load experiments are carried out on two in-service RC hollow slab beams; meanwhile, nonlinear finite element models are built to study the bearing capacity of them. The nonlinear material and shear slip effect of studs are considered in the models. Second, the finite element models are verified, and the numerical simulation results are in good agreement with the experimental results. Finally, the finite element models are adopted to carry out the research on the influence of different steel plate thicknesses on the flexural bearing capacity and ductility.FindingsWhen steel plates of different thicknesses are adopted to reinforce RC hollow slab beams, the bearing capacity increases with the increase of the steel plate thickness in a certain range. But when the steel plate thickness reaches a certain level, bearing capacity is no longer influenced. The displacement ductility coefficient decreases with the increase of steel plate thickness.Originality/valueBased on experimental study, this paper makes an extrapolation analysis of the bearing capacity of hollow slab beams reinforced with steel plates of different thicknesses through finite element simulation and discusses the influence on ductility. This method not only ensures the accuracy of bearing capacity evaluation but also does not need many samples, which is economical to a certain extent. The research results provide a basis for the reinforcement design of similar bridges.

Cutting of a Longitudinally Stiffened Plate by a Wedge

1994 ◽  
Vol 38 (04) ◽  
pp. 340-348 ◽  
Author(s):  
Jeom Kee Paik
Keyword(s):  
Plate Thickness ◽  
Wedge Angle ◽  
Steel Plates ◽  
Test Results ◽  
Stiffened Plate ◽  
Absorbed Energy ◽  
Dimensionless Analysis ◽  
Cutting Length ◽  
Plate Aspect Ratio ◽  
Stiffened Steel

The aim of this study is to obtain test data for longitudinally stiffened steel plates which are quasistatically cut by a rigid wedge, idealizing the deck or bottom platings in ship collision or grounding, and also to derive an empirical formula relating the absorbed energy and cutting length. A series of tests for longitudinally stiffened high-tensile steel plates is conducted, varying several factors, namely plate thickness, plate aspect ratio, angle/shape of wedge tip and property of stiffeners. A total of 50 specimens with thicknesses in the range of 3.4 to 7.8 mm and wedge angles of 15, 30, 45, and 60 deg, including one unstiffened and two horizontally stiffened plate specimens, were tested. The importance of each parameter and its effect on the cutting response are investigated. By dimensionless analysis of the test results obtained here, the energy absorbed while a longitudinally stiffened plate is cut by a wedge is expressed as a function of cutting length, yield stress, equivalent plate thickness, and wedge angle. Incorporation of dynamic effects into the static formula is suggested. A comparison of the proposed solutions with the previous formulas or drop-hammer test results is made.

Study of Continuos Settling Vessels Operating with Suspensions Previously Floculated

2008 ◽  
Vol 591-593 ◽  
pp. 358-361
Author(s):  
J.F. Nunes ◽  
J.R. Lira ◽  
João Jorge Ribeiro Damasceno
Keyword(s):  
Wastewater Treatment ◽  
Solid Particle ◽  
Aluminum Sulfate ◽  
Cylindrical Part ◽  
Continuous Operation ◽  
Circular Section ◽  
Operational Conditions ◽  
The Stability ◽  
Solid Liquid ◽  
Solid Liquid Separation

The settling vessels are equipment destined to solid-liquid separation; usually have continuous operation, with a circular section, presenting one conic and one cylindrical part. They are very used in chemical industries: wastewater treatment, minerals industries; to concentrate or to remove the solids. The solid particle splitting with small granular becomes difficult through the operation of conventional sedimentation. An expedient very used in the industry is the flocculant substance addition, whose objective is to promote the precipitation of particles, with decantation speed is upper than the single one. The present work aim the study of the burst operational conditions that influence the formation and the stability of these aggregates, the flake, the effect of pH and the concentration of flocculant using kaolin suspension and genfloc, that contains aluminum sulfate, as a flocculant; and the capacity of conventional settling vessel, which area of the transversal remains constant, considering this operational conditions.

Longitudinal Strength of Great Lakes Bulk Carriers

1966 ◽  
Vol 3 (02) ◽  
pp. 200-211
Author(s):  
Alex Vedeler
Keyword(s):  
Great Lakes ◽  
Present State ◽  
State Of The Art ◽  
Wave Spectrum ◽  
Statistical Information ◽  
Linear Extrapolation ◽  
Section Modulus ◽  
Bulk Carriers ◽  
Longitudinal Strength ◽  
Steel Weight

Although little statistical information is available regarding the actual wave conditions on the Great Lakes, considerable reductions are possible in the required scantlings of the present and future Great Lakes bulk carriers. Utilizing the available knowledge about the strength of ocean-going vessels and modifying this for the Lakes, rational formulas are developed for the required midship section modulus and moment of inertia. The present Lake strength norm for the large carriers is a linear extrapolation of requirements developed almost 50 years ago and has led to a required midship section modulus considerably in access of what is necessary. The formulas developed in this paper indicate that a saving of around 15 percent in the steel weight is possible within the present state of the art. As more detailed information of the wave spectrum becomes available in the future, further savings should be possible.

Prediction of Deformation to Thin Ship Panels for Different Heat Sources

2001 ◽  
Vol 17 (02) ◽  
pp. 52-61
Author(s):  
H.C. Kuo ◽  
L.J. Wu
Keyword(s):  
Plate Thickness ◽  
Prediction Method ◽  
Steel Plates ◽  
Data Series ◽  
Heat Sources ◽  
Skilled Workers ◽  
Forming Process ◽  
Shipbuilding Industry ◽  
On Line ◽  
The Moment

The increasing use of thin steel plates in manufacturing and the shipbuilding industry has given rise to several issues: massive deformation problems, the need for many skilled workers, and the expense of costs for straightening in on-line processes. This study explains the results of experiments and predicts techniques for the control of deformation in thin panels. The objective of this paper is to explain the use of the G(1,1) Grey method to predict deformation. Bending and buckling are usually the dominant modes of deformation in heat working. It follows angular deformation. De- formation due to different heat sources is discussed. In this paper, laser and torch are used in different constraints, for example, free-free beam and cantilever beam. Many important factors include tiny adjustments during the heat forming process, such as changing the moment speed, intensity of input heating, plate thickness and heating path, to improve manufacture techniques and to predict deformation by data series. For the prediction of deformation, a method to estimate input heating of laser and torch is introduced. The proposed prediction method can be used during the forming process simply and efficiently.

Welding of Thicker Steel Joints of Container Ships

2007 ◽  
Vol 23 (01) ◽  
pp. 46-52
Author(s):  
Osamu Baba ◽  
Yasuhisa Okumoto ◽  
Akinori Abe
Keyword(s):  
Plate Thickness ◽  
High Heat ◽  
Steel Plates ◽  
High Quality ◽  
Butt Welding ◽  
High Efficient ◽  
Steel Maker ◽  
Co2 Welding ◽  
High Heat Input ◽  
Steel Joints

Recently, many container ships have been built worldwide, and the size of them is skyrocketing to 10, 000 TEU (Twenty Equivalent Unit) capacity. As a result, the plate thickness in the area of upper deck torsion box becomes thicker and thicker with higher-strength steel, up to 60 mm, to keep longitudinal strength, and then the welding work becomes more difficult and severe. For such joints of super thick plates IHI Marine United Inc. Kure shipyard has established high-quality and high-efficient welding methods:Development of new steel plates. In order to weld the thicker plates by high heat input such as 450 KJ/cm, new steel plates were applied in cooperation with a steel maker in Japan.Automation of butt welding. Electro-gas arc welding was applied for skin plates, and CO2 welding robot system was also introduced for longitudinals around the torsion box.Establishment of high quality welding practice. Welding without defects became possible by establishing adequate groove shape and welding procedure, as a result of many welding tests and inspections. This paper describes the improved methods and the test results in detail.

scholarly journals An Experimental and Numerical Study on the Flexural Performance of Over-Reinforced Concrete Beam Strengthening with Bolted-Compression Steel Plates: Part II

2019 ◽  
Vol 10 (1) ◽  
pp. 94 ◽  
Author(s):  
Shatha Alasadi ◽  
Zainah Ibrahim ◽  
Payam Shafigh ◽  
Ahad Javanmardi ◽  
Karim Nouri
Keyword(s):  
Failure Modes ◽  
Steel Plate ◽  
Numerical Study ◽  
Load Capacity ◽  
Plate Thickness ◽  
Steel Plates ◽  
Experimental Program ◽  
Failure Characteristics ◽  
Control Beam ◽  
Concrete Failure

This study presents an experimental investigation and finite element modelling (FEM) of the behavior of over-reinforced simply-supported beams developed under compression with a bolt-compression steel plate (BCSP) system. This study aims to avoid brittle failure in the compression zone by improving the strength, strain, and energy absorption (EA) of the over-reinforced beam. The experimental program consists of a control beam (CB) and three BCSP beams. With a fixed steel plate length of 1100 mm, the thicknesses of the steel plates vary at the top section. The adopted plate thicknesses were 6 mm, 10 mm, and 15 mm, denoted as BCSP-6, BCSP-10, and BCSP-15, respectively. The bolt arrangement was used to implement the bonding behavior between the concrete and the steel plate when casting. These plates were tested under flexural-static loading (four-point bending). The load-deflection and EA of the beams were determined experimentally. It was observed that the load capacity of the BCSP beams was improved by an increase in plate thickness. The increase in load capacity ranged from 73.7% to 149% of the load capacity of the control beam. The EA was improved up to about 247.5% in comparison with the control beam. There was also an improvement in the crack patterns and failure modes. It was concluded that the developed system has a great effect on the parameters studied. Moreover, the prediction of the concrete failure characteristics by the FE models, using the ABAQUS software package, was comparable with the values determined via the experimental procedures. Hence, the FE models were proven to accurately predict the concrete failure characteristics.

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