REVIEWOF SHIPSTRUCTURALDETAILS This documenthas been approved for publicreleaseand sale; its distributionis unlimited, SHIP STRUCTURECOMMlllEE 1977 SHIP STRUCTURE COMMITIEE ANINTERAGENCYADVISORY COMMITTEEoEoICATEOTOIMPROVING THESTRUCTUREOFSHIPS MEMBERAGENCIES: ADORESSCORRESPONDENCETO Un,!.d 8!.!,>Cc..,!Gu.,d Secrewy Nov. ! S,. Sy,, cm, Commond shp S,,.,!”,. CO.,”,,,., M<l(tory Se.l,ftCw,,m..d U.S. Coo, ! Gvord Ne.dq. m!ers M.,!,,”?Admi.,s,r.,(n” Wmh, ngmn, D.C. 20590 Am.r,c..B.<,...1 Shipp, ng sR-216 I 5 APR1977 The fabrication of structural design details represents a significant part of shipbuilding costs. These details also represent potential sources of premature failure, fatigue cracking, and brittle fracture. At present, a unifying rationale for design details that includes consideration of reliability and maintainability is not available. The Ship Structure Committee initiated a program with the initial objective to conduct a state-of-the-art study in the area of shipbuilding structural design details. This study was to evaluate and determine design and construction methods currently in use, and to recommend improved and optimal methods. This is a final report of that task and is being published to assist in developing cost effective and safe design details. The Ship Structure Committee expects to consider projects which will provide the rationale for evaluating the reliability and maintain- ability of details. This effort is limited at present to an evalua- t ion of the performance of details on ships in actual service. The results of that study will be published when they are available. W. M“. BENRERT Rear Admiral, U. S. Coast Guard Chairman, Ship Structure Committee — FINAL TECHNICAL REPORT on Project SR-216 “Structural Details Design Review” REVIEW OF SHIP STRUCTURAL DETAILS by R. Glasfeld D. Jordan M. Kerr, Jr. D. Zoner GENERAL DYP~AMICS Quincy Shipbuilding Division under Department of the Navy Naval Sea Systems Command Contract No. NOO024-74-C-5230 This document has been approved for public reLease and sale; its distribution is unlimited. U. S. Coast Guard Headquarters Washington, D.C. 1977 ABSTRACT The review of structural detail design is intended to serve as a summary of the state of the art and a guide to development of tools for design and analysis of these details. The report includes a count of common structural details aboard two mrxlern commercial vessels, and labor estimates for representative sizes of those details intended to provide a total cost per type of detail ranking for those ships Current shipyard practice is reported with sketches and application description of about 160 ship structural details. Design improvements related to shipyard producibility are suggested. The most relevant rules promulgated by technical and classification societies are excerpted, and comparison of rules is illustrated by application to specific examples. Damage induced by poor design or fabrication of details is reviewed and illustrated. The relatively sparse technical literature related to analysis and design of structural details is reviewed and summarized. A framework for fatigue criteria is developed as a suggestion for possible detail strength criteria, and recommendations for future work in the area of detail design are presented. -ii- TABLE OF CONTENTS Page SECTION 1 INTRODUCTION 1-1 SECTION 2 COUNT AND RANKING OF STRUCTURAL DETAILS 2-1 SECTION 3 SHIP STRUCTURAL DETAILS 3-1 SECTION 4 DETAIL DESIGN GUIDELINES 4-1 4.1 General 4-1 4.2 Openings in Ship Hull Structure 4-1 4.2.1 Shell Plating 4-2 4.2.2 Strength Deck Plating 4-6 4.2.3 Bulkhead Plating 4-7 4.2.4 Girders and Other Strength Members 4-8 4.3 Knee and Beam Brackets 4-11 4.3.1 Brackets for Girders and Deep Webs 4-11 4.3.2 Brackets Connecting Rolled Sections 4-15 4.4 Tripping Brackets, Lateral Support 4-15 4.4.1 Unbraced Length of Compression Flange 4-15 4.5 Panel and Web Stiffeners 4-20 4. 5.1 Center and Side Girders 4-20 4.5.2 Floors 4-21 4. 5.3 Web Plate Stiffeners 4-21 4.6 Stanchion Supports and End Connections 4-21 4.6.1 General 4-21 4. 6.2 Compression and Bearing End Connections 4-21 4. 6.3 Tensile End Connections 4-22 4.7 cutouts . 4-24 4.7.1 General 4-24 4. ‘7.2 Lightening Holes 4-24 4. 7.3 Scallops and Snipes 4-24 . 111 TABLE OF CONTENTS (CONTID) Page 4.8 Structural Intersections 4-25 4. 8.1 End Connections 4-25 4.9 List of Common Symbols 4-30 SECTION 5 DAMAGE HISTORY OF STRUCTURAL DETAILS 5-1 5.1 General 5-1 5.2 Brackets 5-1 5.3 Miscellaneous Openings 5-1 5.3.1 Ratholes 5-1 5.3.2 Manholes and Lightening Holes 5-8 5.3.3 Slots and Scallops 5-8 5.4 Local Discontinuities 5-8 5.4.1 Face Plate Transition Pieces 5-8 5.4.2 Hatchway Corners 5-15 5.5 Miscellaneous 5-15 SECTION 6 STRENGTH CRITERIA 6-1 6.1 General 6-1 6.2 Fatigue Criteria 6-3 SECTION 7 LITERATURE SURVEY ON DETAIL DESIGN 7-1 7.1 General 7-1 7.2 Openings 7-1 7.3 frees and Brackets ‘1-l 7.4 Structural Intersections 7-5 SECTION 8 CONCLUSIONS AND RECOMMENDATIONS 8-1 SECTION 9 LIST OF REFERENCES 9-1 APPENDIX A - CLASSIFICATION SOCIETY RULES APPLICABLE A.1 TO STRUCTURAL DETAILS APPENDIX B - COMPARISON OF RULE APPLICATION B-1 APPENDIX C - GLOSSARY c-1 iv LIST OF ILLUSTRATIONS E2!2t Figure 4-1 Flat Bar Reinforcement Along the Edge of 4-3 an Opening Figure 4-2 Flat Bar Reinforcement Around the Inside 4-3 of an Opening Figure 4-3 Openings in the Bottom Shell 4-5 Figure 4-4 Recommended Dimensions of Elliptic or 4-5 Parabolic Corners for Hatchways Figure 4-5 Long Openings or Groups of Long Openings 4-9 All in the Same Section Figure 4-6 Long Openings or Groups of Openings 4-1o Shifted in Relation to Each Other Figure 4-7 Short Openings with Relatively Large 4-1o Spacing in the Same Section or Shifted Figure 4-8 Knee Bracket: Case 1 4-12 Figure 4-9 Knee Bracket: Case 2 4-13 Figure 4-10 Knee Bracket: Case 3 4-14 Figure 4-11 Beam Bracket Connecting Two Sections Neither 4-16 of Which Extend Beyond the Assembly Figure 4-12 Beam Bracket Connecting Two Sections 4-16 Lying in Perpendicular Planes Figure 4-13 Intermediate Beam Bracket Connecting 4-17 Members with Direct Continuity Figure 4-14 Intermediate Beam Bracket Providing 4-17 Continuity of Members Figure 4-15 Two Intermediate Beam Brackets Providing 4-18 Continuity of Members Figure 4-16 Connection Details of Longitudinal to 4-27 Girder Webs v LIST OF ILLUSTRATIONS (CONT ‘D) PaJ@ Figure 5-1 Flexure of Unstiffened Plating About 5-2 Bracket Toe Leading to Cracks Figure 5-2 Cracks Initiating at Brackets Installed on 5-2 Bottom Longitudinals Figure 5-3 Cracks Occurring in Corrugated Bulkheads 5-3 at the Toes of Tripping Brackets Figure 5-4 Cracks Caused by Flexure of Unstiffened 5-3 Bulkhead Plating at Bracket Details Figure 5-5 Use of Horizontal Gusset or Stiffener to 5-4 Stiffen Bulkhead Plating at Points of Flexure Figure 5-6 Use of Doubler Plates to Eliminate Cracks 5-4 at Tripping Brackets on Corrugated Bulkheads Figure 5-7 Poor Bracket Details That Have Led to 5-5 Cracks in Supported Members Figure 5-8 Improved Bracket Details for Figure 5-7 5-6 Figure 5-9 Fracture of Hatch Side Girder and Deck Plate 5-7 at Poor ‘‘Rat hole” Cutout Figure 5-10 Buckled Plating of Transverse Cofferdam 5-9 Figure 5-11 Cracks Occurring in Large Tankers at the 5-1o Junction Between Side Longitudinals and Web Frames Figure 5-12 Cracks in a Deep Tank Stringer 5-11 Figure 5-13 Cracks in Deck Girder due to Poor Positioning 5-12 of Pillar Figure 5-14 Buckling of Bottom Transverse Web Plate 5-13 Figure 5-15 Cracks Occurring at the Junction of Bottom 5-13 Longitudinals and Bottom Transverses Figure 5-16 Cracks Occurring at an Inadequate Transition 5-14 Piece Figure 5-17 Recommended Impr&ements for Face Plate 5-14 Transition Pieces vi LIST OF ILLuSTRATIONS (CONTfD) Page Figure 5-18 Crack Initiating at the Intersection of a 5-16 Transverse Girder and Center Girder Figure 5-19 Fractures Occurring in Hatchway Coamings 5-16 Figure 5-20 Damage Occurrence Rate by Age of Vessel 5-17 Figure 5-21 Cracks in Transverse Rings 5-18 Figure 5-22 Cracks in Notches Through Longitudinals 5-19 Figure 6-1 Stress Histogram 6-4 Figure 6-2 Artificial S-N Diagram 6-8 Figure 6-3 Permissible Stress Histograms 6-9 Figure 7-1 Effective Breadth Ratio for Symmetrical 7-6 Curved Face Plate Figure 7-2 Effective Breadth Ratio for Asymmetrical ‘7-7 Face Plates Fignre 7-3 Detail of Conventional and Crab-Eye Slots 7-9 Figure A-1 Streamlined Hatchway Corner - Recommended A-4 By BV Figure A-2 Dimensions of Elliptic or Parabolic Corners - A-6 Recommended by GL. Figure A-3 Beam Bracket Connecting Two Sections None of A-12 Which Extend Beyond the Assembly - BV Figure A-4 Beam Bracket Connecting Two Sections Lying A-12 in Perpendicular Planes - BV Figure A-5 Intermediate Beam Bracket Connecting Members A-14 to Insure Direct Continuity - BV Figure A-6 Intermediate Beam Bracket Insuring Continuity A-15 of Members Figure A-7 Intermediate Beam Brackets Providing A-15 Continuity of Members Figure A-8 Knee Bracket Config&ation - DNV A-19 Figure A-9 Beam and Knee Bracket Configurations - LR A-20 to A-22 Figure A-10 Flat Bar Reinforcement Along the Edge of an A-42 Opening - DNV Figure A-n Flat Bar Reinforcement Around the Inside of A-42 an Opening - DNV vii LIST OF ILLUSTRATIONS (CONT’D) Page Figure A-12 Flat Bar Reinforcement Arcnmd the Inside G3 of an Opening - LR Figure B-1 Hypothetical Example - Openings in the Shell B-2 Figure B-2 Hy-pathetical Example - Openings in the B-5 Strength Deck on Tankers Figure B-3 Hypothetical Example - Openings in the Strength B-6 Deck on Dry Cargo Ships Figure B-4 Hypothetical Example - Openings