Fatigue Design of Steel and Composite Structures

Alain Nussbaumer is professor of steel construction (laboratory ICOM) at the Swiss Federal Institute of Technology in Lausanne (EPFL). He is a member of CEN TC 250-SC3 and chairman of the Swiss committee SIA 263 on steel structures. He is a member and the former chairman of the technical committee TC6 - Fatigue of ECCS. Luis Borges is a structural engineer at BG Consulting Engineers Ltd., Lausanne. He holds a doctoral degree from EPFL in the domain of fatigue of tubular bridges and is a specialist for steel and steel-concrete composite structures. He is a member of the technical committee TC6 - Fatigue of ECCS. Laurence Davaine is a senior engineer at France's national railway company (SNCF) and is a specialist for steel and steel-concrete composite bridges. She holds a doctoral degree from the French National school of Bridges and Roads (ENPC) in the domain of stability of plated girders for bridge applications. She is a member of the technical committee TC6 - Fatigue of ECCS.

• Foreword xiPreface xiiiAcknowledgments xvSymbology xviiTerminology xxiChapter 1Introduction 11.1 Basis of fatigue design in steel structures 11.1.1 General 11.1.2 Main parameters influencing fatigue life 31.1.3 Expression of fatigue strength 71.1.4 Variable amplitude and cycle counting 101.1.5 Damage accumulation 131.2 Damage equivalent factor concept 151.3 Codes of Practice 181.3.1 Introduction 181.3.2 Eurocodes 3 and 4 181.3.3 Eurocode 9 211.3.4 Execution (EN 1090-2) 231.3.5 Other execution standards 291.4 Description of the structures used in the worked examples 301.4.1 Introduction 301.4.2 Steel and concrete composite road bridge (worked example 1) 311.4.3 Chimney (worked example 2) 341.4.4 Crane supporting structures (worked example 3) 39Chapter 2Application Range and Limitations 432.1 Introduction 432.2 Materials 442.3 Corrosion 442.4 Temperature 452.5 Loading rate 472.6 Limiting stress ranges 47Chapter 3Determination of Stresses And Stress Ranges 513.1 Fatigue loads 513.1.1 Introduction 513.1.2 Road bridges 523.1.3 Railway bridges 573.1.4 Crane supporting structures 593.1.5 Masts, towers, and chimneys 613.1.6 Silos and tanks 703.1.7 Tensile cable structures, tension components 703.1.8 Other structures 713.2 Damage equivalent factors 723.2.1 Concept 723.2.2 Critical influence line length 753.2.3 Road bridges 763.2.4 Railway bridges 823.2.5 Crane supporting structures 843.2.6 Towers, masts and chimneys 923.3 Calculation of stresses 933.3.1 Introduction 933.3.2 Relevant nominal stresses 943.3.3 Stresses in bolted joints 963.3.4 Stresses in welds 963.3.5 Nominal stresses in steel and concrete composite bridges 993.3.6 Nominal stresses in tubular structures (frames and trusses) 1003.4 Modified nominal stresses and concentration factors 1043.4.1 Generalities 1043.4.2 Misalignments 1073.5 Geometric stresses (Structural stress at the hot spot) 1133.5.1 Introduction 1133.5.2 Determination using FEM modelling 1153.5.3 Determination using formulas 1173.6 Stresses in orthotropic decks 1193.7 Calculation of stress ranges 1223.7.1 Introduction 1223.7.2 Stress range in non-welded details 1233.7.3 Stress ranges in bolted joints 1253.7.4 Stress range in welds 1313.7.5 Multiaxial stress range cases 1333.7.6 Stress ranges in steel and concrete composite structures 1373.7.7 Stress ranges in connection devices from steel and concrete composite structures 1423.8 Modified Nominal stress ranges 1463.9 Geometric stress ranges 148Chapter 4Fatigue Strength 1574.1 Introduction 1574.1.1 Set of fatigue strength curves 1574.1.2 Modified fatigue strength curves 1624.1.3 Size effects on fatigue strength 1634.1.4 Mean stress influence 1654.1.5 Post-weld improvements 1654.2 Fatigue detail tables 1664.2.1 Introduction 1664.2.2 Non-welded details classification (EN 1993-1-9, Table 8.1) 1664.2.3 Welded plated details classification (general comments) 1684.2.4 Longitudinal welds, (built-up sections, EN1993-1-9 Table 8.2), including longitudinal butt welds 1694.2.5 Transverse butt welds (EN1993-1-9 Table 8.3) 1704.2.6 Welded attachments and stiffeners (EN 1993-1-9 Table 8.4), and load-carrying welded joints (EN 1993-1-9 Table 8.5) 1714.2.7 Welded tubular details classification (EN 1993-1-9 Tables 8.6 and 8.7) 1744.2.8 Orthotropic deck details classification (EN 1993-1-9 Tables 8.8 and 8.9) 1754.2.9 Crane girder details (EN 1993-1-9 Table 8.10) 1764.2.10 Tension components details (EN 1993-1-11) 1764.2.11 Geometric stress categories (EN 1993-1-9, Annex B, Table B.1) 1794.2.12 Particular case of web breathing, plate slenderness limitations 1804.3 Determination of fatigue strength or life by testing 180Chapter 5Reliability and Verification 1835.1 Generalities 1835.2 Strategies 1855.2.1 Safe life 1855.2.2 Damage tolerant 1855.3 Partial factors 1865.3.1 Introduction 1865.3.2 Action effects partial factor 1875.3.3 Strength partial factor 1885.4 Verification 1925.4.1 Introduction 1925.4.2 Verification using the fatigue limit 1935.4.3 Verification using damage equivalent factors 2015.4.4 Verification using damage accumulation method 2075.4.5 Verification of tension components 2095.4.6 Verification using damage accumulation in case of two or more cranes 2105.4.7 Verification under multiaxial stress ranges 212Chapter 6Brittle Fracture 2216.1 Introduction 2216.2 Steel quality 2236.3 Relationship between different fracture toughness test results 2246.4 Fracture concept in EN 1993-1-10 2296.4.1 Method for toughness verification 2296.4.2 Method for safety verification 2316.4.3 Flaw size design value 2346.4.4 Design value of the action effect stresses 2366.5 Standardisation of choice of material: maximum allowable thicknesses 238References 247Annex A Standards for steel construction 257Annex B Fatigue detail tables with commentary 263B.1 Plain members and mechanically fastened joints (EN 1993-1-9, Table 8.1) 264B.2 Welded built-up sections (EN 1993-1-9, Table 8.2) 267B.3 Transverse butt welds (EN 1993-1-9, Table 8.3) 269B.4 Attachments and stiffeners (EN 1993-1-9, Table 8.4) 272B.5 Load carrying welded joints (EN 1993-1-9, Table 8.5) 274B.6 Hollow sections (T ≤ 12.5 mm) (EN 1993-1-9, Table 8.6) 277B.7 Lattice girder node joints (EN 1993-1-9, Table 8.7) 279B.8 Orthotropic decks - closed stringers (EN 1993-1-9, Table 8.8) 281B.9 Orthotropic decks - open stringers (EN 1993-1-9, Table 8.9) 283B.10 Top flange to web junction of runway beams (EN 1993-1-9, Table 8.10) 284B.11 Detail categories for use with geometric (hot spot) stress method (EN 1993-1-9, Table B1) 286B.12 Tension components 288B.13 Review of orthotropic decks details and structural analysis 290Annex C Maximum Permissible Thicknesses Tables 295C.1 Maximum permissible values of element thickness t in mm (EN 1993-1-10, Table 2.1) 295C.2 Maximum permissible values of element thickness t in mm (EN 1993-1-12, Table 4) 296