Design Loads Used for Direct Strength Assessment of Merchant Ship Structures

2004 ◽  
Author(s):  
Tingyao Zhu ◽  
Toshiyuki Shigemi
Keyword(s):  
Irregular Waves ◽  
Estimation Methods ◽  
Regular Waves ◽  
Bulk Carrier ◽  
Ship Structures ◽  
Strength Assessment ◽  
Hull Girder ◽  
Merchant Ship ◽  
Bulk Carriers ◽  
Design Loads

This paper summarizes the results of extensive research on the design loads used for strength assessment of merchant ship structures such as tankers, bulk carriers and container ships. The main aim of the research was to develop practical estimation methods of design loads having rational technical backgrounds acting on primary structural members of tankers, bulk carriers and container ships. During this study: 1) The design sea states that closely resemble the actual sea states which are considered as the most severe for hull structures are proposed. 2) The practical estimation methods of the design sea states are proposed by parametric studies using the results of series calculation of representative merchant ships. 3) The practical estimation methods of design regular waves resulting in the same level of stresses with that induced in irregular waves under the design sea states are proposed. 4) The practical estimation methods of the design loads such as ship motions, accelerations, hull-girder bending moments and hydrodynamic pressures that are induced under design regular waves are briefly introduced. The findings in this study have been summarized and implemented in the new design standards for tanker, bulk carrier and container ship structures. (Guidelines for Tanker Structures, 2001, Nippon Kaiji Kyokai. Guidelines for Bulk Carrier Structures, 2002, Nippon Kaiji Kyokai. Guidelines for container Carrier Structures, 2003, Nippon Kaiji Kyokai.)

Design Loads Used for Direct Strength Assessment of Merchant Ship Structures

2006 ◽  
Vol 129 (2) ◽  
pp. 120-130 ◽  
Author(s):  
Tingyao Zhu ◽  
Toshiyuki Shigemi
Keyword(s):  
Irregular Waves ◽  
Estimation Methods ◽  
Regular Waves ◽  
Bulk Carrier ◽  
Ship Structures ◽  
Strength Assessment ◽  
Hull Girder ◽  
Merchant Ship ◽  
Bulk Carriers ◽  
Design Loads

This paper summarizes the results of extensive research on the design loads used for strength assessment of merchant ship structures such as tankers, bulk carriers, and container ships. The main aim of the research was to develop practical estimation methods of design loads having rational technical backgrounds acting on primary structural members of tankers, bulk carriers, and container ships. During this study we will do the following. (1) The design sea states that closely resemble the actual sea states which are considered as the most severe for hull structures are proposed. (2) The practical estimation methods of the design sea states are proposed by parametric studies using the results of series calculation of representative merchant ships. (3) The practical estimation methods of design regular waves resulting in the same level of stresses as that induced in irregular waves under the design sea states are proposed. (4) The practical estimation methods of the design loads such as ship motions, accelerations, hull-girder bending moments, and hydrodynamic pressures that are induced under design regular waves are briefly introduced. The findings in this study have been summarized and implemented in the new design standards for tanker, bulk carrier, and container ship structures (“Guidelines for Tanker Structures,” 2001, Nippon Kaiji Kyokai; “Guidelines for Bulk Carrier Structures,” 2002, Nippon Kaiji Kyokai; “Guidelines for Container Carrier Structures,” 2003, Nippon Kaiji Kyokai).

scholarly journals Predictions of Ship Extreme Hydroelastic Load Responses in Harsh Irregular Waves and Hull Girder Ultimate Strength Assessment

2019 ◽  
Vol 9 (2) ◽  
pp. 240 ◽  
Author(s):  
Jialong Jiao ◽  
Yong Jiang ◽  
Hao Zhang ◽  
Chengjun Li ◽  
Chaohe Chen
Keyword(s):  
Ultimate Strength ◽  
Time Domain ◽  
Three Dimensional ◽  
Direct Calculation ◽  
Wave Force ◽  
Irregular Waves ◽  
Restoring Force ◽  
Strength Assessment ◽  
Hull Girder ◽  
Rule Approach

In this paper, the hydroelastic motion and load responses of a large flexible ship sailing in irregular seaways are predicted and the hull girder ultimate strength is subsequently evaluated. A three-dimensional time-domain nonlinear hydroelasticity theory is developed where the included nonlinearities are those arising from incident wave force, hydrostatic restoring force and slamming loads. The hull girder structure is simplified as a slender Timoshenko beam and fully coupled with the hydrodynamic model in a time domain. Segmented model towing-tank tests are then conducted to validate the proposed hydroelasticity theory. In addition, short-term and long-term predictions of ship responses in irregular seaways are conducted with the help of the developed hydroelastic code in order to determine the extreme design loads. Finally, a simplified strength-check equation is proposed, which will provide significant reference and convenience for ship design and evaluation. The hull girder ultimate strength is assessed by both the improved Rule approach and direct calculation.

Ultimate Strength of a Capesize Bulk Carrier in Hogging and Alternate Hold Loading Condition

2010 ◽  
Author(s):  
Zhi Shu ◽  
Torgeir Moan
Keyword(s):  
Ultimate Strength ◽  
Loading Condition ◽  
Fe Analysis ◽  
Fe Model ◽  
Bulk Carrier ◽  
Local Pressure ◽  
Local Loads ◽  
Hull Girder ◽  
Bulk Carriers ◽  
Global And Local

The ultimate hull girder strength of a Capesize bulk carrier under combined global and local loads in hogging and alternate loading condition (AHL) is evaluated using nonlinear finite element (FE) analysis with ABAQUS software. A three-cargo-hold FE model with fine mesh in the middle cargo hold is developed for the nonlinear FE analysis. The initial geometrical imperfections are introduced in the double bottom of the middle cargo hold. Both material and geometrical nonlinearities are taken into account in the FE model. The most critical situation for the longitudinal strength assessment of bulk carriers in hogging is the AHL condition with middle cargo hold empty under combined global and local loads. The local loads, i.e. the external sea pressure and internal cargo pressure are adopted according to Common Structural Rules for bulk carriers (CSR-BC). The ultimate hull girder strength with various local pressure load levels is investigated for the heavy cargo AHL in hogging condition. It is found that the ultimate strength of the hull girder can be significantly reduced due to the action of the local pressure loads compared with that obtained under pure hogging bending.

Buckling and Ultimate Strength Assessments of Ship Structures

2013 ◽  
Author(s):  
Shengming Zhang
Keyword(s):  
Ultimate Strength ◽  
Fe Analysis ◽  
Development Work ◽  
Ship Structures ◽  
Element Analysis ◽  
Strength Assessment ◽  
Stiffened Panels ◽  
Development History ◽  
Bulk Carriers ◽  
Oil Tankers

This paper presents buckling and ultimate strength assessment methods for ship structures. Buckling and collapsing analysis approaches for plates, stiffened panels and hull girders are described and their development history and employments in ship design assessments are reviewed and discussed. Examples using non-linear finite (FE) element analysis are given and comparisons between results obtained by formulae and FE analysis are carried out. Lloyd’s Register’s recent research and development work on ultimate strength and its applications to existing oil tankers and bulk carriers are also presented.

scholarly journals Ultimate Limit State Design Technology for Aluminum Multi-Hull Ship Structures

2005 ◽  
Author(s):  
Jeom Kee Paik ◽  
Owen F. Hughes ◽  
Paul E. Hess ◽  
Celine Renaud
Keyword(s):  
Ultimate Strength ◽  
Limit State ◽  
Extensive Study ◽  
Stiffened Panel ◽  
Ultimate Limit State ◽  
Ship Structures ◽  
Strength Assessment ◽  
Hull Girder ◽  
National University ◽  
Ultimate Limit

The present paper is a summary of recent research and developments related to some core ultimate limit state (ULS) technologies for design and strength assessment of aluminum multi-hull ship structures, jointly undertaken by Pusan National University, Virginia Tech, U.S. Naval Surface Warfare Center and Alcan Marine. An extensive study on the subject has been undertaken by the authors theoretically, numerically and experimentally. Methods to analyze hull girder loads / load effects, stiffened panel ultimate strength and hull girder ultimate strength of aluminum multi-hull ship structures are developed in the present study. Application examples of the methodologies for the ULS structural design and strength assessment of a hypothetical 120m long all aluminum catamaran fast ship structure are presented. Important insights and conclusions developed from the present study are summarized. Some of the comparisons have shown that 5383 called Sealium (a patented Alcan Marine alloy) is superior to the standard aluminum alloy 5083 in terms of material properties, ULS characteristics and welding performance. It is our hope that the methods developed from the present study will be useful for ULS design and strength assessment of aluminum multi-hull ship structures.

Bulk Carrier Safety

1996 ◽  
Vol 33 (04) ◽  
pp. 309-318
Author(s):  
Karen Frystock ◽  
Jack Spencer
Keyword(s):  
International Association ◽  
Failure Criteria ◽  
Bulk Carrier ◽  
Strength Criteria ◽  
Strength Assessment ◽  
Critical Areas ◽  
Marine Industry ◽  
Hull Structure ◽  
Bulk Carriers ◽  
Assessment Procedures

During the past ten years, more than 700 crewmen have died as a result of Bulk Carrier casualties. Following a rash of 25 Bulk Carrier losses in 1990 and 1991, The American Bureau of Shipping (ABS), The International Association of Classification Societies (IACS), and various other segments of the marine industry initiated measures in an attempt to correct this situation. During the next several years another 11 Bulk Carrier losses (resulting in the death of 174 crewmen), indicated that these measures, although improving the situation, did not go far enough to solve the problem. A close examination of the vessels involved indicated that the overwhelming majority of the bulk carriers were in excess of 15 years old. While inadequate maintenance and improper loading have been likely contributory factors, it is apparent that present BulkCarrier designs have not matched expectations as these vessels age. At ABS a study to investigate the response of the Bulk Carrier hull structure was undertaken in an attempt to understand the causes of the structural weaknesses which may have contributed to these losses. In applying a first principles approach of using representative and realistic dynamic loads, the critical areas, including hold frames and end brackets, corrugated transverse bulkheads, cross deck structures and fore end structures were studied. This study resulted in the development of a new complete, flexible, and integrated strength criteria for design and assessment of Bulk Carrier hull structures. The approach encompasses:the loading criteria,the strength criteria for minimum scantling requirements, andthe strength assessment procedures incorporating failure criteria dealing with material yielding, buckling/ultimate strength and fatigue. In this paper, an overview of this new strength standard is presented and the procedures to rectify problem areas unique to bulk carriers are discussed.

scholarly journals Time Scale for Scour Beneath Pipelines Due to Long-Crested and Short-Crested Nonlinear Random Waves Plus Current

2021 ◽  
Vol 9 (2) ◽  
pp. 114
Author(s):  
Dag Myrhaug ◽  
Muk Chen Ong
Keyword(s):  
Time Scale ◽  
Current Flow ◽  
Irregular Waves ◽  
Wave Crest ◽  
Random Wave ◽  
Random Waves ◽  
Flow Conditions ◽  
Regular Waves ◽  
Nonlinear Random Waves ◽  
2D And 3D

This article derives the time scale of pipeline scour caused by 2D (long-crested) and 3D (short-crested) nonlinear irregular waves and current for wave-dominant flow. The motivation is to provide a simple engineering tool suitable to use when assessing the time scale of equilibrium pipeline scour for these flow conditions. The method assumes the random wave process to be stationary and narrow banded adopting a distribution of the wave crest height representing 2D and 3D nonlinear irregular waves and a time scale formula for regular waves plus current. The presented results cover a range of random waves plus current flow conditions for which the method is valid. Results for typical field conditions are also presented. A possible application of the outcome of this study is that, e.g., consulting engineers can use it as part of assessing the on-bottom stability of seabed pipelines.

Structural Safety Assessment of a 1100 TEU Container Ship, Based on a Enhanced Long Term Fatigue Analysis

2014 ◽  
Vol 1036 ◽  
pp. 935-940
Author(s):  
Leonard Domnisoru ◽  
Ionica Rubanenco ◽  
Mihaela Amoraritei
Keyword(s):  
Safety Assessment ◽  
Safety Evaluation ◽  
Irregular Waves ◽  
Structural Safety ◽  
Random Wave ◽  
Wave Loads ◽  
Strength Assessment ◽  
Integrated Method ◽  
Hydroelastic Response

This paper is focused on an enhanced integrated method for structural safety assessment of maritime ships under extreme random wave loads. In this study is considered an 1100 TEU container test ship, with speed range 0 to 18 knots. The most comprehensive criteria for ships structural safety evaluation over the whole exploitation life is based on the long term ship structures analysis, that includes: stress hot-spots evaluation by 3D/1D-FEM hull models, computation of short term ship dynamic response induced by irregular waves, long term fatigue structure assessment. The analysis is enhanced by taking into account the ships speed influence on hydroelastic response. The study includes a comparative analysis on two scenarios for the correlation between the ships speed and waves intensity. The standard constant ship speed scenario and CENTEC scenario, with total speed loss at extreme waves condition, are considered. Instead of 20 years ship exploitation life estimated by classification societies rules from the long term structural safety criteria, the enhanced method has predicted more restrictive values of 14.4-15.7 years. The numerical analyses are based on own software and user subroutines. The study made possible to have a more realistic approach of ships structural strength assessment, for elastic and faster ships as container carriers, in compare to the standard one based only on naval rules, delivering a method with higher confidence in the designed structural safety.

Time-Variant Redundancy of Ship Structures

2011 ◽  
Vol 55 (03) ◽  
pp. 208-219 ◽  
Author(s):  
Alberto Decó ◽  
Dan M. Fragopol ◽  
Nader M. Okasha
Keyword(s):  
Bending Strength ◽  
Progressive Collapse ◽  
Probability Of Failure ◽  
Optimization Approach ◽  
Ship Structures ◽  
Hull Girder ◽  
Reliability Method ◽  
Ultimate Bending Strength ◽  
Ultimate Failure ◽  
Bending Failure

An efficient procedure for the computation of the redundancy of ship structures is presented. The changes in the redundancy due to corrosion section loss over time are also studied. Moreover, uncertainties associated with structural geometry, material properties, and loading, are accounted for. In order to calculate the redundancy index, the probability of failure of the first component and the probability of ultimate failure of the whole hull girder must be evaluated. The probability of failure is computed using a hybrid Latin Hypercube - second-order reliability method (SORM) technique. The deterministic analyses during the simulations are conducted using an optimization approach for computing the ultimate bending strength of the whole hull girder and the progressive collapse method for computing the first bending failure.

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