AISC DESIGN GUIDE 21-2006 Welded Connections-A Primer for Engineers.pdf

1、21Steel Design GuideWelded Connections A Primer for EngineersDG21_cover.indd 1 6/21/2006 8:21:32 AM21Steel Design GuideWelded ConnectionsA Primer For EngineersDUANE K. MILLER, Sc.D., P.E.The Lincoln Electric CompanyCleveland, OhioAMERICAN INSTITUTE OF STEEL CONSTRUCTION, INC.Copyright 2006byAmerican

2、 Institute of Steel Construction, Inc.All rights reserved. This book or any part thereofmust not be reproduced in any form without thewritten permission of the publisher.The information presented in this publication has been prepared in accordance with recognized engineering principles and is for ge

3、neral information only. While it is believed to be accurate, this information should not be used or relied upon for any specific application without compe-tent professional examination and verification of its accuracy, suitablility, and applicability by a licensed professional engineer, designer, or

4、 architect. The publication of the material contained herein is not intended as a representation or warranty on the part of the American Institute of Steel Construction or of any other person named herein, that this information is suitable for any general or particular use or of freedom from infring

5、ement of any patent or patents. Anyone making use of this information assumes all liability arising from such use.Caution must be exercised when relying upon other specifications and codes developed by other bodies and incorporated by reference herein since such material may be modified or amended f

6、rom time to time subsequent to the printing of this edition. The Institute bears no responsi-bility for such material other than to refer to it and incorporate it by reference at the time of the initial publication of this edition.Printed in the United States of AmericaFirst Printing: June 2006DESIG

7、N GUIDE 21 / WELDED CONNECTIONS A PRIMER FOR ENGINEERS/ iiiAcknowledgmentsThe author would like to thank The Lincoln Electric Com-pany for the use of many of the gures provided in this document and the following reviewers for their insightful comments and suggestions:Brad DavisFred BreismeisterRoger

8、 L. BrockenbroughCharles J. CarterJason EricksenStephen M. HerlacheWladyslaw Jaxa-RozenLawrence KloiberChristopher HewittKeith LandwehrMichael MayesRon MengDavis ParsonsDean PhillipsDavid T. RickerThomas J. SchlayBill SeguiRobert E. Shaw, Jr. Victor ShneurRaymond H.R. TideGary VioletteKenneth Wiesne

9、rDESIGN GUIDE 21 / WELDED CONNECTIONS A PRIMER FOR ENGINEERS/ vTable of Contents1. INTRODUCTION .11.1 IMPORTANCE OF WELDING 11.2 SCOPE OF WELDING .11.3 WELDING-RELATED CODES AND SPECIFICATIONS1.3.1 AISC Specication for Structural Steel Buildings .11.3.2 AWS D1.1 Structural Welding CodeSteel 21.3.3 A

10、ISC Seismic Provisions for Structural Steel Buildings 21.3.4 AWS D1.8 Structural Welding CodeSeismic Supplement .31.3.5 AWS D1.3 Structural Welding CodeSheet Steel 31.3.6 Other AWS D1 Codes 32. WELDING AND THERMAL CUTTINGPROCESSES 52.1 INTRODUCTION .52.1.1 Requirements for Welding .52.1.2 Arc Weldin

11、g as Compared to Other Welding Processes .62.1.3 Process Issues and Concerns for the Engineer .62.2 SMAW .82.2.1 Fundamentals .82.2.2 Equipment 82.2.3 Consumables 92.2.4 Electrode Classication System 92.2.5 Low-Hydrogen SMAW Electrodes 102.2.6 Care and Storage of Low-Hydrogen Electrodes 102.2.7 Proc

12、ess Advantages/Limitations 122.2.8 Applications .122.3 FCAW 122.3.1 Fundamentals .122.3.2 Equipment 132.3.3 Consumables 132.3.4 Electrode Classication .142.3.5 FCAW Advantages and Limitations 152.3.6 FCAW-G Advantages and Limitations 162.3.7 FCAW-G Applications .162.3.8 FCAW-S Advantages and Limitat

13、ions .162.3.9 FCAW-S Applications 162.3.10 FCAW-S Intermix Concerns 162.4 SAW 172.4.1 Fundamentals .172.4.2 Equipment 182.4.3 SAW Consumables 182.4.4 Electrode and Flux Classication 192.4.5 Flux Recovery 202.4.6 Crushed Slag 202.4.7 Process Advantages and Limitations .202.4.8 Applications .212.5 GMA

14、W 212.5.1 Fundamentals .212.5.2 Equipment 212.5.3 Consumables 222.5.4 Electrode Classication System 222.5.5 Shielding Gas .222.5.6 Modes of Transfer 232.5.7 Process Advantages and Limitations .242.5.8 Applications .252.6 ESW/EGW 252.6.1 Fundamentals .252.6.2 Equipment 262.6.3 Consumables 262.6.4 Ele

15、ctrode Classication .262.6.5 Process Advantages and Limitations .262.6.6 Applications .272.7 GTAW 272.8 ARC STUD WELDING 272.9 THERMAL CUTTING PROCESSES 282.9.1 Oxyfuel Gas Cutting and Gouging 292.9.2 Plasma Arc Cutting and Gouging 292.9.3 Air Carbon Arc Gouging and Cutting 303. WELDED CONNECTIONS 3

16、13.1 JOINTS 313.2 WELD TYPESGENERAL 313.3 COMPLETE JOINT PENETRATION (CJP) GROOVE WELDS 313.3.1 CJP Groove Weld Backing 323.3.2 Single-Sided vs. Double-Sided Welds .343.3.3 Groove Weld Preparations .343.3.4 Spacer Bars 343.4 PARTIAL JOINT PENETRATION (PJP)GROOVE WELDS 343.4.1 Effective Throats for P

17、JP Groove Welds .353.4.2 Minimum PJP Groove Weld Sizes .353.4.3 Restrictions on the Use of PJP Groove Welds .353.4.4 Required Filler Metal Strength for PJP-Groove Welds 363.4.5 Flare-V and Flare-Bevel Groove Welds .363.4.6 Single-Sided vs. Double-Sided Welds .363.4.7 PJP-Groove Weld Details .363.5 F

18、ILLET WELDS .363.5.1 Minimum Size of Fillet Welds .373.5.2 Maximum Size of Fillet Welds 383.5.3 Minimum Fillet Weld Lengths .383.5.4 Maximum Fillet Weld Lengths 383.5.5 Intermittent Fillet Welds 383.5.6 Penetration in Fillet Welds .393.5.7 Longitudinal vs. Transverse Fillet Welds 393.5.8 Combined Lo

19、ngitudinal vs. Transverse Welds .403.5.9 End Returns (Boxing) 403.5.10 Weld Termination (Fillet Welds) 413.5.11 Fillet Welds and Fitup 423.6 PLUG/SLOT WELDS .423.7 INTERACTION OF JOINT TYPES AND WELD TYPES .433.8 SELECTION OF WELD TYPES .433.9 WELD DETAILS 453.9.1 Weld Tabs .453.9.2 Weld Access Hole

20、s .453.9.3 Fillers .463.9.4 Welds and Mechanical Fasteners .463.9.5 Strength of Welds in Combinations .473.9.6 k-Area Detailing .473.10 LAMELLAR TEARING AND JOINT DETAILS .483.11 REQUIRED FILLER METAL STRENGTH 483.11.1 Matching Filler Metal 483.11.2 Undermatching Filler Metal 483.11.3 Overmatching 4

21、93.12 DETERMINING WELD STRENGTH .503.12.1 CJP Groove Welds .503.12.2 PJP Groove Welds 503.12.3 Fillet Welds 503.12.4 Plug/Slot Welds 513.13 SPECIAL WELDS 513.13.1 Arc Spot Welds (Puddle Welds,Deck Welds) .513.13.2 Repair Welds 513.13.3 Seal Welds 523.13.4 Tack Welds .533.13.5 Temporary Welds .543.13

22、.6 Compatibility of Weld Metals 543.14 SPECIFIC REQUIREMENTS FOR VARIOUS JOINTS .543.14.1 Butt Joints 543.14.2 Corner Joints 543.14.3 T-Joints .553.14.4 Lap Joints .553.15 WELDING SYMBOLS 553.16 SAMPLE CALCULATIONS 574. METALLURGICAL ISSUES 594.1 INTRODUCTION .594.2 STEELPROPERTIES OF INTEREST 594.3

23、 DESCRIPTIONS OF STEEL GROUPS .604.3.1 AWS D1.1 Prequalied Steels .604.3.2 AWS D1.1 Approved Steels .604.3.3 AWS D1.1 Unlisted Steels .604.3.4 AISC Specication Treatment of Unidentied Steels .60vi/DESIGNGUIDE21/ WELDED CONNECTIONS A PRIMER FOR ENGINEERSDESIGN GUIDE 21 / WELDED CONNECTIONS A PRIMER F

24、OR ENGINEERS/ vii4.4 WELDING REQUIREMENTS FOR SPECIFIC STEELS .604.4.1 Weathering Steels 604.4.2 Quenched and Tempered Steels .614.4.3 Historical (Obsolete) Steels .624.5 WELDING NONSTRUCTURAL STEELS .634.5.1 Anchor Rods 634.5.2 Bolts and Nuts 644.5.3 Stainless Steel to Steel .644.5.4 Cast Iron 644.

25、5.5 Wrought Iron .654.5.6 Steel Castings .655. WELD CRACKING 675.1 INTRODUCTION .675.2 SHRINKAGE AND RESTRAINT 675.2.1 Shrinkage .675.2.2 Constraint .675.3 TYPES OF WELD CRACKS .685.3.1 Centerline Cracking .685.3.2 Heat-Affected Zone Cracking 725.3.3 Transverse Cracking 745.4 LAMELLAR TEARING .755.5

26、 REDUCING SHRINKAGE STRESSES 775.6 REDUCING RESTRAINT .785.7 POST-WELDING STRESS REDUCTION MEASURES 786. DISTORTION 796.1 INTRODUCTION .796.2 CAUSES OF DISTORTION .796.3 DISTORTION CONTROL .806.3.1 General .806.3.2 Angular Distortion .816.3.3 Transverse Shrinkage .826.3.4 Longitudinal Shortening 826

27、.3.5 Twisting .836.3.6 Longitudinal Sweep or Camber .836.3.7 Buckling and Warping .846.3.8 Rotational Distortion .846.4 SPECIALIZED DISTORTION CONTROL MEASURES 856.4.1 Adding Restraint 856.4.2 Weld Placement .866.4.3 Welding Sequence 867. WELDING PROCEDURE SPECIFICATIONS .897.1 INTRODUCTION .897.2 W

28、RITING WELDING PROCEDURE SPECIFICATIONS 897.3 USING WELDING PROCEDURE SPECIFICATIONS 897.4 PREQUALIFIED WELDING PROCEDURE SPECIFICATIONS 907.5 QUALIFIED WELDING PROCEDURE SPECIFICATIONS 917.6 EFFECTS OF WPS VARIABLES 927.6.1 Amperage .927.6.2 Arc Voltage 927.6.3 Travel Speed 927.6.4 Wire Feed Speed

29、937.6.5 Electrode Extension .937.6.6 Contact Tip to Work Distance 937.6.7 Electrode Diameter 937.6.8 Polarity .937.6.9 Heat Input 937.6.10 Preheat and Interpass Temperature 947.6.11 Post-Heat 947.6.12 Stress Relief .948. WELD QUALITY . 958.1 INTRODUCTION .958.2 TYPES OF WELD DISCONTINUITIES .958.2.1

30、 Planar DiscontinuitiesWeld and Base Metal .958.2.2 Volumetric DiscontinuitiesSpecic to the Weld .978.2.3 Volumetric Discontinuities External to the Weld .1008.2.4 Metallurgical Deciencies .100viii/DESIGNGUIDE 21 / WELDED CONNECTIONS A PRIMER FOR ENGINEERS9. WELD INSPECTION . 1019.1 INTRODUCTION .10

31、19.2 VISUAL INSPECTION (VT) .1019.2.1 Visual Inspection Before Welding .1019.2.2 Visual Inspection During Welding .1029.2.3 Visual Inspection After Welding 1029.3 NONDESTRUCTIVE TESTING GENERAL 1029.4 PENETRANT TESTING (PT) 1029.5 MAGNETIC PARTICLE INSPECTION (MT) 1039.6 RADIOGRAPHIC INSPECTION (RT)

32、 1049.7 ULTRASONIC INSPECTION (UT) .10410. SEISMIC WELDING ISSUES . 10710.1 INTRODUCTION .10710.2 SPECIFICATIONS AND CODES 10810.3 SEISMIC WELDING TERMINOLOGY .10810.4 SPECIAL CONNECTION DETAILS 10910.5 FILLER METAL REQUIREMENTS .11010.6 WELDER QUALIFICATION TESTS 11110.7 NONDESTRUCTIVE TESTING .111

33、11. FATIGUE CONSIDERATIONS 11311.1 INTRODUCTION .11311.2 STRESS RANGE 11311.3 CONNECTION GEOMETRY 11611.4 COMPUTATIONS 11811.5 INSPECTION ISSUES .11911.6 SPECIAL FABRICATION/ERECTIONREQUIREMENTS 11912. SPECIAL WELDING APPLICATIONS 12112.1 WELDING ON ANCHOR RODS 12112.1.1 General .12112.1.2 Extending

34、 Anchor Rods .12112.1.3 Welding Anchor Rod to Base Plates 12112.2 WELDING ON COATED STEELS 12212.2.1 General .12212.2.2 Galvanized Materials .12212.2.3 Testing 12212.2.4 Ventilation 12312.3 WELDING ON HEAVY SECTIONS .12312.4 WELDING ON HEAVILY RESTRAINED MEMBERS .12412.5 WELDING HSS .12512.5.1 Intro

35、duction 12512.5.2 Connections and HSS Member Size .12612.5.3 Overall Congurations of HSS Assemblies .12612.5.4 Cutting and Preparing Joints in HSS 12612.5.5 Welding HSS .12712.6 WELDING AESS .12712.7 SHOP VS. FIELD WELDING 12812.8 WELDING ON EXISTING STRUCTURES 12812.8.1 General .12812.8.2 General W

36、elding Precautions .12812.8.3 Welding on Members under Load .12912.8.4 Repair of Plastically Deformed Steel 12912.9 HEAT SHRINKING 13013. THE ENGINEERS ROLE IN WELDED CONSTRUCTION 13113.1 INTRODUCTION .13113.2 CONTRACT DOCUMENTS 13113.2.1 Design Drawings .13213.2.2 Static vs. Cyclic Loading .13213.2

37、.3 Inspection Requirements .13213.2.4 Alternate Acceptance Criteria 13313.2.5 Notch Toughness Requirements 13313.2.6 Welding on Existing Structures .13313.2.7 Structural Details .13413.2.8 Certication of Welding Materials .13413.3 APPROVALS 13413.3.1 Background 13413.3.2 New Materials and Processes

38、13513.3.3 Routine Items .13513.3.4 Practices Requiring Review .13513.3.5 Practices That May or May Not Be Acceptable .13613.4 UNEXPECTED CIRCUMSTANCES 13613.4.1 Background 13613.4.2 Base Metal Discontinuities 136DESIGN GUIDE 21 / WELDED CONNECTIONS A PRIMER FOR ENGINEERS/ ix13.4.3 Fit-up and Alignme

39、nt Problems .13713.4.4 Welding Problems 13713.4.5 Post-Welding Corrections 13714. ECONOMY IN WELDING . 13914.1 INTRODUCTION .13914.2 SELECTION OF PROPER WELD TYPE 13914.2.1 CJP Groove Welds vs. Alternatives .13914.2.2 Fillet Welds vs. PJP Groove Welds 14014.2.3 Combination PJP/Fillet Weld Option .14

40、014.3 PROPER DETAILING OF WELDS .14114.3.1 Fillet Welds: Leg Size vs. Length 14114.3.2 Fillet Welds: Intermittent vs. Continuous .14114.3.3 CJP Groove Welds: Single vs. Double Sided .14214.3.4 CJP Groove Weld Details: Included Angle vs. Root Opening 14214.3.5 CJP Groove Welds: V and Bevel vs. U and

41、J .14514.3.6 PJP-Groove Welds: Single vs. Double Sided .14514.3.7 Flare Groove Welds .14614.3.8 Shop vs. Field Welding 14614.3.9 Welded vs. Bolted Connections .14615. WELDING SAFETY 147REFERENCES 149x / DESIGN GUIDE 21 / WELDED CONNECTIONS A PRIMER FOR ENGINEERSDESIGN GUIDE 21 / WELDED CONNECTIONS A

42、 PRIMER FOR ENGINEERS/ 11. Introduction1.1 IMPORTANCE OF WELDINGWelding has developed into an established and essential tool of the steel construction industry. Before welding was possible, rivets were used to create structural members and connect them. Today, welding is used to construct members su

43、ch as plate girders and box sections, as well as to connect structural members together reliably and cost effectively. Along with the contributions of high-strength bolts, welding has rendered riveting obsolete.Welding permits shapes, plates, and even steel castings to be connected in nearly endless

44、 combinations. Steel com-ponents can be directly connected without the need for me-chanical fasteners and the associated connection materials. Welded connections are aesthetically pleasing, directly sat-isfying “form follows function” criteria. Steels of various strength levels or thicknesses can be

45、 joined together, opti-mizing designs by strategically placing materials of higher capacity into regions of higher demand. The versatility of welding gives the designer greater freedom than any other method of joining.Connections are critical to the performance of structural systems, and welded conn

46、ections are no exception. Accord-ingly, when welding is improperly used, whether through in-correct design or detailing of the connection, or when a weld is made improperly during fabrication or erection, the con-nection may fail. Nearly everyone involved with the design, detailing, fabrication, ere

47、ction, and inspection of welded structures needs to have some knowledge of welding, and this Guide contains basic coverage of the major welding- related issues associated with steel building construction. The principles set forth are essential to achieving depend-able, cost-effective welded connecti

48、ons in steel structures.1.2 SCOPE OF WELDINGWelding engineering is a complex science, involving design and design details, metallurgy, the production aspects of the various welding processes, and inspection. Design involves the selection of joint types, weld types, sizing of welds, and selection of

49、the required weld metal strength, as well as the base metal grades and types. Design details include weld access holes, copes, backing, one-sided versus two-sided welds, groove weld geometries (e.g., V versus bevel), and weld tabs. Metallurgy addresses material composition, physical and mechanical properties, compatibility of materi-als, preheat for welding, interpass temperature, analysis of weld cracking, and whether postweld heat treatments will be required. Selecting the best welding process for a given application is a complex