First book to discuss the analysis of structural steel connections by Finite Element Analysis - which provides fast, efficient, and flexible checking of these vital structural components
The analysis of steel structures is complex - much more so than the analysis of similar concrete structures. There are no universally accepted rules for the analysis of connections in steel structures or the analysis of the stresses transferred from one connection to another. This book presents a general approach to steel connection analysis and check, which is the result of independent research that began more than fifteen years ago. It discusses the problems of connection analysis and describes a generally applicable methodology, based on Finite Element Analysis, for analyzing the connections in steel structures. That methodology has been implemented in software successfully, providing a fast, automatic, and flexible route to the design and analysis of the connections in steel structures.
Steel Connection Analysis explains several general methods which have been researched and programmed during many years, and that can be used to tackle the problem of connection analysis in a very general way, with a limited and automated computational effort. It also covers several problems related to steel connection analysis automation.
- Uses Finite Element Analysis to discuss the analysis of structural steel connections
- Analysis is applicable to all connections in steel structures
- The methodology is the basis of the commercially successful CSE connection analysis software
- Analysis is fast and flexible
Structural engineers, fabricators, software developing firms, university researchers, and advanced students of civil and structural engineering will all benefit from Steel Connection Analysis.
Table of Contents
Preface xv
1 Introduction 1
1.1 An Unsolved Problem 1
1.2 Limits of Traditional Approaches 2
1.2.1 Generality 2
1.2.2 Member Stress State Oversimplification 3
1.2.3 Single Constituent Internal Combined Effects Linearization 4
1.2.4 Single Constituent External Combined-Effects Neglect 7
1.2.5 Neglecting Eccentricities 8
1.2.6 Use of Envelopes 9
1.2.7 Oversimplification of Plastic Mechanisms Evaluation 11
1.2.8 Evaluation of Buckling Phenomena 13
1.3 Some Limits of the Codes of Practice 14
1.3.1 Problem of Coded Standards 14
1.3.2 T-Stub in Eurocode 3 15
1.3.3 Eurocode 3 Component Model 17
1.3.4 Distribution of Internal Forces 20
1.3.5 Prying Forces 20
1.3.6 Block Tearing 21
1.4 Scope of This Book 21
1.5 Automatic Modeling and Analysis of 3D Connections 23
1.6 Acknowledgments 24
References 24
2 Jnodes 27
2.1 BFEM 27
2.2 From the BFEM to the Member Model 29
2.2.1 Physical Model and the Analytical Model 29
2.2.2 Member Detection: Connection Codes 31
2.2.3 An Automatic Algorithm for Straight Prismatic Member Detection 34
2.2.4 Member Data Structure 36
2.2.5 Member Classification at a Node 36
2.2.6 Member Mutual Alignment Coding 37
2.3 Jnodes 40
2.3.1 Need for the Jnode Concept 40
2.3.2 Jnode Definition 41
2.4 Jnode Analytics 42
2.4.1 Classification of Jnodes 42
2.4.2 Simple Jnodes 42
2.4.3 Hierarchical Jnodes 42
2.4.4 Central Jnodes 43
2.4.5 Cuspidal Jnodes 43
2.4.6 Tangent Jnodes 44
2.4.7 Constraints 45
2.4.8 Summary of Jnode Classification 46
2.4.9 Setting Connection Codes: Examples 46
2.5 Equal Jnodes Detection 49
2.5.1 Toponode 49
2.5.2 Jnode Data Structure 49
2.5.3 Superimposable Member Couples 50
2.5.4 Criteria to Assess Jnodes Equality 51
2.5.5 Algorithm to Find Equal Jnodes 52
2.5.6 Examples 55
2.6 Structural Connectivity Indices 56
2.7 Particular Issues 59
2.7.1 Symmetries 59
2.7.2 Splitting of Jnodes 60
2.7.3 Mutual Interaction of Different Jnodes, Jnode Clusters 61
2.7.4 Tolerances 63
2.8 Jclasses 63
References 64
3 A Model for Connection 65
3.1 Terminology 65
3.2 Graphs of Connections 66
3.3 Subconstituents vs Layouts 69
3.4 Classification of Connections 70
Reference 72
4 Renodes 73
4.1 From Jnode to Renode Concept 73
4.2 BREP Geometrical Description of 3D Objects 73
4.3 The Scene 75
4.3.1 Generality 75
4.3.2 Members 77
4.3.3 Typical Fittings 78
4.3.4 Connectors 79
4.4 Dual Geometry 83
4.5 Automatic Connection Detection 85
4.5.1 Faces in Contact 85
4.5.2 Bolt Layouts 86
4.5.3 Weld Layouts 89
4.6 Elementary Operations 91
4.7 Renode Logic and the Chains 93
4.7.1 Minimum Compliance Criteria for Renode Good Design 93
4.7.2 Chains 94
4.7.3 Finding Chains 96
4.8 Prenodes 102
4.9 After Scene Creation 103
5 Pillars of Connection Analysis 105
5.1 Equilibrium 105
5.1.1 Generality 105
5.1.2 Statics of Free Rigid Bodies 108
5.2 Action Reaction Principle 111
5.3 Statics of Connections 115
5.3.1 Equilibrium of Members in Renodes: Proper and Dual Models 115
5.3.2 Force Packets for Compound Members 119
5.3.3 Primary Unknowns: Iso-, Hypo-, and Hyperconnectivity 124
5.4 Static Theorem of Limit Analysis 127
5.5 The Unsaid of the Engineering Simplified Methods 130
5.6 Missing Pillars of Connection Analysis 130
5.6.1 Buckling 131
5.6.2 Fracture 147
5.6.3 Slip 150
5.6.4 Fatigue 152
5.7 Analysis of Connections: General Path 153
References 154
6 Connectors: Weld Layouts 155
6.1 Introduction 155
6.2 Considerations of Stiffness Matrix of Connectors 156
6.3 Introduction to Weld Layouts 160
6.4 Reference Systems and Stresses for Welds 162
6.5 Geometrical Limitations 165
6.5.1 Penetration Weld Layouts 165
6.5.2 Fillet Weld Layouts 166
6.6 Penetration-Weld Layouts (Groove Welds) 167
6.6.1 Generality 167
6.6.2 Simple Methods to Evaluate the Stresses 168
6.6.3 Weld Layout Cross-Section Data 170
6.6.4 Stiffness Matrix 172
6.6.5 Special Models 185
6.6.6 Example 188
6.7 Fillet-Welds Weld Layouts 196
6.7.1 The Behavior of Fillet Welds 196
6.7.2 Numerical Tests of Fillet Welds in the Linear Range 207
6.7.3 The Stiffness Matrix of a Single Fillet Weld 212
6.7.4 Instantaneous Center of Rotation Method in 3D 214
6.7.5 Computing the Stresses in Fillet Welds from the Forces Applied to the Layout 231
6.7.6 Fillet Welds Using Contact and Friction 233
6.8 Mixed Penetration and Fillet Weld Layouts 235
References 235
7 Connectors: Bolt Layouts and Contact 237
7.1 Introduction to Bolt Layouts 237
7.2 Bolt Sizes and Classes 238
7.3 Reference System and Stresses for Bolt Layouts 240
7.4 Geometrical Limitations 243
7.4.1 Eurocode 3 244
7.4.2 AISC 360-10 244
7.5 Not Preloaded Bolt Layouts (Bearing Bolt Layouts) 244
7.5.1 Shear and Torque 244
7.5.2 Axial Force and Bending 249
7.6 Preloaded Bolt Layouts (Slip Resistant Bolt Layouts) 266
7.6.1 Preloading Effects 266
7.6.2 Shear and Torque 274
7.6.3 Axial Force and Bending 275
7.7 Anchors 277
7.8 Stiffness Matrix of Bolt Layouts and of Single Bolts 282
7.8.1 Generality 282
7.8.2 Not Preloaded Bolts 283
7.8.3 Preloaded Bolts 292
7.8.4 Non-Linear Analysis of Bolts 293
7.9 Internal Force Distribution 296
7.9.1 General Method 296
7.9.2 Bearing Surface Method to Compute Forces in Bolts 302
7.9.3 Instantaneous Center of Rotation Method 306
7.9.4 Examples 307
7.10 Contact 316
References 317
8 Failure Modes 319
8.1 Introduction 319
8.2 Utilization Factor Concept 320
8.3 About the Specifications 326
8.4 Weld Layouts 328
8.4.1 Generality 328
8.4.2 Penetration Weld Layouts 328
8.4.3 Fillet Weld Layouts 332
8.5 Bolt Layouts 337
8.5.1 Resistance of Bolt Shaft 337
8.5.2 Sliding and Resistance of No-Slip Connections 342
8.5.3 Pull-Out of Anchors, or Failure of the Anchor Block 345
8.6 Pins 346
8.6.1 Eurocode 3 346
8.6.2 AISC 360-10 347
8.7 Members and Force Transferrers 347
8.7.1 Generality 347
8.7.2 Local Failure Modes 350
8.7.3 Fracture Failure Modes 358
8.7.4 Global Failure Modes 373
References 382
9 Analysis: Hybrid Approach 385
9.1 Introduction 385
9.2 Some Basic Reminders About FEM Analysis of Plated-Structures 386
9.2.1 FEM Analysis as an Engineering Tool 386
9.2.2 Linear Models 387
9.2.3 Linear Buckling Analysis 388
9.2.4 Material Non-Linearity 390
9.2.5 Geometrical Non-Linearity 392
9.2.6 Contact Non-Linearity 394
9.2.7 Non-Linear Analysis Control 396
9.3 IRFEM 400
9.3.1 Goal 400
9.3.2 Hypotheses 401
9.3.3 Construction 402
9.3.4 Examples 408
9.3.5 Results 411
9.3.6 Remarks on the Use of IRFEM 413
9.4 Connector Checks 418
9.4.1 Weld Checks 418
9.4.2 Bolt Resistance Checks 419
9.4.3 Pull-Out Checks 419
9.4.4 Slip Checks 419
9.4.5 Prying Forces 419
9.5 Cleats and Members Non-FEM Checks 426
9.5.1 Action Reaction Principle 426
9.5.2 Bolt Bearing 428
9.5.3 Punching Shear 428
9.5.4 Block Tearing 428
9.5.5 Simplified Resistance Checks 429
9.6 Single Constituent Finite Element Models 430
9.6.1 Remarks on the Finite Element Models of Single Constituents (SCOFEM) 430
9.6.2 Stiffeners 432
9.6.3 Meshing 433
9.6.4 Constraints 437
9.6.5 Loading 439
9.6.6 Members: Deciding Member-Stump-Length 443
9.6.7 Compatibility Issues 444
9.7 Multiple Constituents Finite Element Models (MCOFEM) 445
9.7.1 Goal and Use 445
9.7.2 Mesh Compatibility Between Constituents and Connector Elements 446
9.7.3 Saturated Internal Bolt Layouts and Contact Non-Linearity 447
9.7.4 Constraints 448
9.7.5 Stabilizing Springs and Buckling of Members 448
9.7.6 Need for Rechecks 449
9.8 A Path for Hybrid Approach 449
References 450
10 Analysis: Pure FEM Approach 451
10.1 Losing the Subconnector Organization 451
10.2 Finite Elements for Welds 455
10.2.1 Introduction 455
10.2.2 Penetration Welds 457
10.2.3 Fillet Welds 460
10.3 Finite Elements for Bolts 463
10.3.1 Introduction 463
10.3.2 Bolts in Bearing: No Explicit Bolt-Hole Modeling 464
10.3.3 Bolts in Bearing: Explicit Bolt-Hole Modeling 465
10.3.4 Preloaded Bolts: No Explicit Bolt-Hole Modeling 468
10.3.5 Preloaded Bolts: Explicit Bolt-Hole Modeling 468
10.3.6 Effect of the Bending Moments in Bolt Shafts 469
10.3.7 Example: A Bolted Splice Joint Using PFEM 469
10.4 Loads 478
10.4.1 PFEM 478
10.4.2 MCOFEM 479
10.5 Constraints 480
10.5.1 PFEM 480
10.5.2 MCOFEM 480
10.6 Checking of Welds and Bolts 480
10.7 Checking of Components 481
10.8 Stiffness Evaluation 482
10.9 Analysis Strategies 484
Reference 484
11 Conclusions and Future Developments 485
11.1 Conclusions 485
11.2 Final Acknowledgments 486
11.2.1 Reasons of This Project 486
11.3 Future Developments 487
References 488
Appendix 1: Conventions and Recalls 489
A1.1 Recalls of Matrix Algebra, Notation 489
A1.2 Cross-Sections 490
A1.3 Orientation Matrix 492
A1.4 Change of Reference System 493
A1.5 Pseudocode Symbol Meaning 493
Appendix 2: Tangent Stiffness Matrix of Fillet-Welds 495
A2.1 Tangent Stiffness Matrix of a Weld Segment 495
A2.2 Modifications for Weld Segments Using Contact 499
A2.3 Tangent Stiffness Matrix of a Weld Layout for the Instantaneous Center of Rotation Method 500
Appendix 3: Tangent Stiffness Matrix of Bolts in Shear 503
A3.1 Tangent Stiffness Matrix of a Bolt 503
A3.2 Tangent Stiffness Matrix of a Bolt Layout for the Instantaneous Center of Rotation Method 505
Symbols and Abbreviations 507
Index 513
