Marine Structures Research Recommendations Recommendations for the Interagency Ship Structure Committee's FY 1995 and Later-Years Research Program (1995) / Chapter Skim
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RESEARCH PROGRAM DEVELOPMENT
RESEARCH PROGRAM DEVELOPMENT
Pages 12-40
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From page 12... ...
The working groups' specific concerns, activities, and common interest in structural reliability are as follows. Design Work Group-extreme wave loads, higher-order forces, and responses; ice, groundings, and collisions; large-scale structural tests; operations-oriented monitoring systems; modeling errors in loads and responses; procedures for fatigue stress computations; design process improvement; producibility; and reliability-based design codes.
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From page 13... ...
Relationships Among Strategic Plan, Technology Areas, and Thrust Areas The Table ~ relationships between CMS-recommended projects and thrust areas are further expanded in Table 2 and Figure I Table 2 relates the goals of the strategic plan to thrust areas of the CMS and to the technology areas of the multiyear research program.
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From page 14... ...
Research Projects STRATEGIC PLAN: NATIONAL GOALS THRUST AREA TECHNOLOGY AREAS 96-1 Evaluation of Effect of Construction Tolerances on Vessel Strength A Predictive Methodology for the Evaluation of Residual Stress and Distortion in Double Hull Ship Structures Failure Definition for Structural Reliability Assessment 96-4 Probability-Based Design (Phase 5~: Load and Resistance Factor Design (LRFD) Methods for Ship Structures In Situ Nondestructive Evaluation of Fatigue and Fracture Properties for Aging Ship Structures (9SM-H)
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96-17 Sea-Operational Profile for Structural Reliability Assessment 96-18 Condition Assessment and Optimal Maintenance of Existing Surface Coating System for Tankers 96-19 Development of a Sensor for Evaluating Corrosion in Areas Not Easily Accessed for Inspection (95M-D) 96-20 Experiments on Stiffened Panel Collapse and Estimation of Modeling Bias Environmental Risk Reliability Materials Reduction Criteria Maritime Industry Support Safety and Integrity Producibility/ Design Competitiveness Environmental Risk Composites Materials Reduction Criteria Safety and Integrity Safety and Integrity Environmental Risk Reduction Safety and Integrity Reliability Maritime Industry Support Maritime Industry Support Safety and Integrity Composites Materials Criteria Materials Criteria Producibility/ Competitiveness Producibility/ Competitiveness Design Fabrication and Maintenance Reliability Reliability Safety and Integrity Inspection/ Maintenance Maritime Industry Support Safety and Integrity Inspection/ Maintenance Safety and Integrity Reliability Maritime Industry Support Fabrication and Maintenance Fabrication and Maintenance Materials Criteria Reliability 15
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FIGURE :t Recommendations of the Committee on Marine Structures for the Ship Structure Committee's research program. Sheet .e SYMPOSL\, ADVANCED CONCEPTS, AND LONG-RANGE PLANNING I FY 1995 1 FY 1996 1 FY 1997 1 FY 1998 1 FY 1999 CMS-SSSC Meeting SR-1363 Symposium and Workshop on the Prevention of Fracture in Ship Structures Ship Structure Committee/ Society of Naval Architects and Marine Engineers Ship Structure Symposium Quality and Human/Organizational Errors in Marine Structures Note: The following project designations are used: SR-XXXX Ongoing SSC project 96-XX Recommended project for E;YFS 1996-97 96D-XX Recommended Design project for out years 96M-XX Recommended Materials project for out years 1 11 |1 51 _.
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I THRUST AREA: Producibility / Competitiveness 1 I FY 1995 1 FY 1996 1 FY 1997 1 FY 1998 1 FY 1999 | Design Technology SR-1350 Reexamination of Design Criteria for Stiffened Plate Panels SR-1354 Grounding Protection of Tankers SR-1364 Guidelines for Evaluation of Finite Element Models and Results SR-1368 Compensation for Openings in Structural Members SR-1372 Evaluation of Marine Structures Education in North America 96-1 Evaluation of Effect of Construction Tolerances to Vessel Strength 96-7 Workshop on Industry Standards for Integrated Ship Design Software Interfaces 96-8 Alternative Stiffening Systems for Double-Skin Tankers 96-9 Rupture Resistance of Cargo Tanks of Double Hull Tankers to Low Energy Impacts (95-12)
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; FY 1995 1 FY 1996 1 FY 1997 1 FY 1998 1 FY 1999 Fabrication and Maintenance Technology SR-1343 Optimized Weld Metal Properties for Ship Structures SR-1351 Hull Structure Concepts for Improved Producibility 96-2 A Predictive Methodology for the Evaluation of Residual Stress and Distortion in Double Hull Ship Structures 96-16 Weldable Primers for Ship Construction (9SM-V) 96M-B The Definition of Local Brittle Zones in the Heat-Affected-Zones of Low-Alloy High-Strength Steel Weldments 96M-G Development of High Performance Tubular/Flux Cored Weld Filler Metal 96M-H Effect of Weld Surface Quality on Hull Structural Integrity 96M-N Atlas of Welding Properties and Procedures 96M-Q Performance and Optimized Weld Metal Properties of Domestically Produced AC/D Q Steels (JMS/9SM-E)
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Criteria for Ship Structures 96-20 Experiments on Stiffened Panel Collapse and Estimation of Modeling Bias 96D-O Probability-Based Design (Phase 6~: Novel Hull Forms and Environments Loads and Response Technolo~v SR-1342 Hydrodynamic Impact on Displacement Ship Hulls .. SR-1359 U.S.-Russian Cooperative Research Effort l (Extreme Waves and Wave Impact Forces)
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Design Technology SR-1346 Improved Ship Hull Structural Details 179 1 Relative to Fatigue SR-1353 The Role of Human Error in the Design, l ~I Construction, and Reliability of Marine Structures SR-1373 Hull Response Monitoring System 96D-U Statistical Characteristics of Strength Properties of Currently Used Steel in Marine Structures 96D-V Statistical Characteristics of Geometric Properties of Currently Used Plates and Structural Shapes in Marine Structures Materials Criteria Technolon, SR-1349 Ductile Fracture Models for the Prediction of Fracture Behavior of Ship Structure Details SR-1379 Weld Detail Fatigue Life Improvement Techniques 96-10 Fatigue and Fracture Criteria for Assessing Safety in Double-Hulled Ships (95-8) 96-14 Crack-Arrest Toughness of Steel Weldments 96M-D Specification of Toughness for High Performance Steels in Designs Requiring Ductile Fracture Fabrication and Maintenance Technology SR-1356 Strength Assessment of Pitted Plate Panels Initiate Project FIGURE :t Recommendations of the Committee on Marine Structures for the Ship Structure Committee's research program.
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SR-1377 Commercial Ship Design and Fabrication for Corrosion Control (94-4) 96-6 Methodology for Systematic Collection of Corrosion Data Using Ultrasonic Thickness Measurements of Ship Structures (9STC-B Revised)
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Ship Structures 96M-S Retrofit of Marine Cathodic Protection Systems (9SM-A) 96M-U Threshold and Near-Threshold Corrosion Fatigue Testing of Marine Steels (9SM-N)
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96-13 Durability of Polymer-Based Composites in Marine Environments (9SM-S) 96M-K Implementation Plan for Use of PolymerBased Composites in Ship Structures 96M-W Analysis and Design Technology Development for Marine Composite Structures (9SM-T)
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Composites have been identified by the CMS as a thrust area upon which special attention should be focused. Recommended for FYs 1996-97 is a program that identifies applications for composite use in ship structure and develops a plan to incorporate these materials into new and existing ship structures, Project 96M-K, Implementation Plan for Use of Polymer-Based Composites in Ship Structures." Parallel efforts that focus on structural safety and integrity have been recommended for FYs 1996-97.
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exploitation of nondestructive techniques for evaluating durability of aging ship structures. To provide a more technological basis for the evaluation of the potential for failure in double-hulled ships, Project 96-10, UFatigue and Fracture Criteria for Assessing Safety in Double-Hulled Ships," will use current approaches to fracture and fatigue prediction to evaluate that potential and wall incorporate those approaches into the design process for double-hulled ships.
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To look at potential for life extension, Project 96-5, UIn-Serv~ce Nondestructive Evaluation of Fatigue and Fracture Properties for Aging Ship Structures, wall examine a new technology for assuring the continued safe life for aging ships. Corrosion and Corrosion Fatigue Prevention of corrosion of marine structures is important because of the increased cost associated with the maintenance and repair of corroded structure.
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The proposed Project 96D-P, UStudent Design Competition for innovative Producible Marine Structures,n is intended to foster interest among students of naval architectural schools in the design of ship structures. The project will provide opportunities for several undergraduate students to obtain grants to perform structural designs for a practical marine structure.
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Several projects have been proposed to study the strength characteristics of ship structures. Project 96-l, Devaluation of Effect of Construction Tolerances to Vessel Strength, will study the effect of structural imperfections during construction on ship structural behavior and strength.
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Yet another project on the double-bottom structure, Project 96-~l, Evaluation and Assessment of Fillet Welding of Double Bottom Structure to Resist Pollution in Grounding, would specifically investigate fillet weld design not covered by the Massachusetts Institute of Technology program on Tanker Safety. To enhance the performance of ship structure, Project SR-13 46, Ulmproved Ship Hull Structural Details Relative to Fatigue," began in 1992; Project SR-1350, Reexamination of Design Criteria for Stiffened Plate Panels," began in 1993.
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It was a first step to reduce the risk of failures due to human error and to establish procedures and guidelines for considering the effects of human errors in design and the appropriate reformulation of structural design criteria. Similar attention should be focused on developing methods to integrate human and organizational error into ship structure construction and maintenance.
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From page 31... ...
Consequently, the probability of detecting surface defects visually wall be investigated in Project SR-1375, Detection Probability Assessment of Visual Inspection of Ships." This project is intended to provide guidance as to the effectiveness of visual inspection. Once the reliability of visual inspection to determine surface quality is quantified, the impact of surface quality on weld integrity would be addressed in proposed Project 96M-H, Effect of Weld Surface Quality on Hull Structural Integrity." Finally, there are instances in which it is necessary to augment visual inspection by ultrasonic testing or radiographic testing.
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From page 32... ...
ports in the future. The proposed Project 96-2, PA Predictive Methodology for the Evaluation of Residual Stress and Distortion in Double Hull Ship Structures," should help in identifying means for minimizing the deleterious effects of residual stresses on ship structures and, thus, also add to the abilities of U.S.
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The CMS recommends that Project 96M-B, UThe Definition of Local Brittle Zones in the Heat-Affected Zones of Low Alloy High-Strength Steel Weldments,~ be undertaken to define the nature and causes of local brittle zones. The results of this project would lead to improved understanding of the nature of the zones and their causes, resulting in more-realistic criteria for weldable steels and welding processes in marine structures.
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From page 34... ...
This research is intended to evaluate a novel method to perform wet-weld repairs with potential for better properties, minimum porosity, and lower operator skills than conventional wet-arc welding. Inspection and Integrity Marine structural integrity during construction and service is a continuing concern of the CMS, especially with the extended service life of existing structures.
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Repair of Marine Structures Routine maintenance and repair intervals for marine structures affect service life and operating costs. However, the lack of adequate repair techniques can reduce structural integrity, shorten service life, or require costly replacements.
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The development and implementation of probability-based structural design procedures have been under way in other areas since the early 1960s. In addition to the existing design procedure that is based on the concept of a working stress, a probabilitybased load and resistance factor design procedure was issued by the American Institute for Steel Construction in 1986, with a second edition published in 1993.
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Probabili~-BasedF Design Approach for Ship Structures Phase 1: Demonstration Project A demonstration project, UProbability-Based Ship Design Procedures: A Demonstration" (SSC-368) , was completed in 1993.
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Methods for Ship Structures," will include a rigorous and complete code calibration for the design of ship structure. The resulting load and resistance factor design criteria, including all failure modes, will be written in a code style that is suitable for the direct use of practicing engineers.
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From page 39... ...
This project will determine whether the current data base, existing structural reliability literature, and practice contain the necessary elements to probabilistically assess the performance and safely of ship structures that have unusual forms or are subject to uncommon environments. Reliability of Existing Ship Structures Knowledge of the probabilistic characteristics of important failure modes would be useful in developing rational probability-based design criteria.
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