Cable Supported Bridges

Niels Jørgen Gimsing & Christos Georgakis, Technical University of Denmark, LyngbyProfessor Gimsing is Professor Emeritus in the Department of Civil Engineering at the Technical University of Denmark and a Consulting Bridge Engineer. He consulted on the design for numerous landmark bridges including the Femern Bridge, third bridge across the Firth of Forth in Scotland, the Messina Strait Bridge and the 47km long motorway bridge across the Gulf of Thailand, and was a Finalist in the Millennium Bridge Competition for a pedestrian bridge across the Thames at St. Paul's Cathedral. He has won numerous design, teaching and research awards for his work within the structural engineering community and is the author of Cable Supported Bridges 2e (Wiley, 1997) and co-author of The Messina Strait Bridge (CRC, 2009).Dr. Christos Georgakis is Associate Professor in Structural Engineering and Prof Gimsing’s teaching successor at DTU. He has particular experience in relation to dynamic actions from his work at the Wind Tunnel Laboratory in Copenhagen and is also involved in several research projects dealing with the dynamics of slender bridges such as the Millennium Bridge in London.

"Pleasingly, this book is comprehensively referenced for those wishing to delve into further detail. While not a manual for detailed design, the contents of the book provide a comprehensive knowledge base for students and experienced engineers seeking to expand their understanding of these structures, which themselves continually challenge the boundaries of what is possible." (Engineering and Computational Mechanics, 11 October 2013)"The book is well organised into components: cables, pylons and anchorages, and goes into every possible detail ... The book strikes a perfect balance between theory and practice. Professors Gimsing and Georgakis set out to give us an authoritative book about the evolution, trends and technical response of cable-supported bridges, and they have achieved that well." (The Structural Engineer, 1 April 2012)"Comprehensively updated to discuss improvements in technology in the fourteen years since its last printing, the third edition of this volume on the theory and design of cable supported bridges provides a detailed, element-by-element discussion of the core principles of suspension bridge design." (Book News, 1 April 2012)

• Preface to the Third Edition ix Introduction 11 Evolution of Cable Supported Bridges 72 Cables 852.1 Basic Types of Cables 852.1.1 Helical bridge strands (spiral strands) 852.1.2 Locked-coil strands 872.1.3 Parallel-wire strands for suspension bridge main cables 882.1.4 New PWS stay cables 902.1.5 Parallel-strand stay cables 912.1.6 Bar stay cables 932.1.7 Multi-strand stay cables 942.1.8 Parallel-wire suspension bridge main cables 972.1.9 Comparison between different cable types 1012.2 Corrosion Protection 1022.2.1 Suspension bridge main cables 1022.2.2 Stay cables 1052.3 Mechanical Properties 1092.3.1 Static strength 1092.3.2 Relaxation 1112.3.3 Fatigue strength 1112.3.4 Hysteresis of helical strands 1132.4 The Single Cable as a Structural Element 1152.4.1 Transversally loaded cable 1152.4.2 Axially loaded cable 1262.5 Static Analysis of Cables 1312.5.1 Equation of state for a cable subjected to vertical load 1322.5.2 Stay cable under varying chord force 1352.5.3 Limit length and efficiency ratio of a stay cable 1432.6 Bending of Cables 1482.7 Dynamic Behaviour of the Single Cable 1573 Cable System 1653.1 Introduction 1653.1.1 Pure cable systems 1653.1.2 Cable steel quantity comparison 1703.1.3 Stability of the cable system 1733.2 Suspension System 1793.2.1 Dead load geometry 1793.2.2 Preliminary cable dimensions 1803.2.3 Quantity of cable steel 1823.2.4 Quantity in the pylon 1843.2.5 Total cost of cable system and pylon 1853.2.6 Optimum pylon height 1853.2.7 Size effect 1873.2.8 Structural systems 1883.3 Fan System 2023.3.1 Anchor cable 2023.3.2 Preliminary cable dimensions 2053.3.3 Quantity of cable steel 2063.3.4 Quantity in the pylon 2083.3.5 Simplified expressions 2083.3.6 Total cost of cable systems and pylons 2093.3.7 Comparison between suspension and fan system 2093.3.8 Inclined pylons 2103.3.9 Deformational characteristics 2133.3.10 Structural systems 2173.3.11 Reduction of sag variations 2213.4 Harp System 2223.4.1 Dead load geometry 2253.4.2 Intermediate supports 2263.4.3 Preliminary cable dimensions 2273.4.4 Quantity of cable steel 2293.4.5 Quantity of the pylon 2293.4.6 Simplified expressions 2313.4.7 Total cost 2313.4.8 Structural systems 2313.5 Hybrid Suspension and Cable Stayed System 2353.6 Multi-Span Cable System 2393.6.1 True multi-span cable supported bridges 2413.6.2 Non-traditional multi-span suspension bridges 2463.6.3 Fixing of column-type pylons to piers 2493.6.4 Triangular pylon structures 2503.6.5 Horizontal tie cable between pylon tops 2583.6.6 Comparison between deflections of different multi-span cable stayed systems 2613.7 Cable Systems under Lateral Loading 2653.8 Spatial Cable Systems 2723.9 Oscillation of Cable Systems 2783.9.1 Global oscillations 2784 Deck (Stiffening Girder) 2874.1 Action of the Deck 2874.1.1 Axial stiffness 2874.1.2 Flexural stiffness in the vertical direction 2874.1.3 Flexural stiffness in the transverse direction 2894.1.4 Torsional stiffness 2914.2 Supporting Conditions 2914.3 Distribution of Dead Load Moments 2994.3.1 The dead load condition 3024.4 Cross Section 3104.4.1 Bridge floor 3104.4.2 Cross section of the deck 3104.4.3 Cross section of stiffening trusses 3284.5 Partial Earth Anchoring 3394.5.1 Limit of span length for self-anchored cable stayed bridges 3434.5.2 Axial compression in the deck of the self anchored cable stayed bridge 3444.5.3 Lateral bending of the deck 3464.5.4 Partial earth anchoring of a cable stayed bridge 3464.5.5 Improving the lateral stability 3484.5.6 Construction procedure for partially earth anchored cable stayed bridges 3495 Pylons 3535.1 Introduction 3535.2 Structural Behaviour of the Pylon 3535.3 Pylons Subjected Primarily to Vertical Forces from the Cable System 3675.4 Pylons Subjected to Longitudinal Forces from the Cable System 3995.5 Cross Section 4056 Cable Anchorage and Connection 4136.1 Anchoring of the Single Strand 4136.2 Connection between Cable and Deck 4276.3 Connection between Main Cable and Hanger 4336.4 Connection between Cable and Pylon 4426.5 Connection between Cable and Anchor Block 4527 Erection 4637.1 Introduction 4637.2 Construction of Pylons 4637.3 Erection of Suspension Bridge Main Cables 4727.4 Erection of Stay Cables 4867.5 Deck Erection - Earth Anchored Suspension Bridges 4897.6 Deck Erection - Self Anchored Cable Stayed Bridges 5018 Aerodynamics 5178.1 Historical Overview 5178.1.1 Nineteenth-century bridge failures 5178.1.2 Tacoma Narrows Bridge collapse 5178.1.3 The Carmody Board 5208.1.4 The Fyksesund Bridge 5208.2 The Bridge Deck and Pylon 5208.2.1 Torsional divergence 5208.2.2 Coupled flutter 5248.2.3 Buffeting 5268.2.4 Vortex-shedding 5318.2.5 Wind tunnel testing 5328.2.6 During construction 5378.2.7 Effects of vehicles 5388.2.8 Pylon aerodynamics 5388.2.9 Vibration control 5418.2.10 Future trends 5438.3 Cables 5448.3.1 Introduction 5448.3.2 Incidences of wind-induced cable vibrations 5448.3.3 Rain-wind-induced vibrations 5458.3.4 Dry galloping 5468.3.5 Scruton number 5498.3.6 Wake galloping 5508.3.7 Aerodynamic countermeasures 5518.3.8 Mechanical damping 5838.3.9 Cable aerodynamic damping 5578.3.10 Cross ties 5579 Particular Issues 5599.1 Pedestrian-Induced Vibrations 5599.1.1 Lateral vibrations 5599.1.2 Vertical vibrations 5629.1.3 Serviceability limit states 5659.1.4 Vibration control 5679.2 Seismic Design 5689.2.1 Earthquake intensity 5699.2.2 Pylon design 5699.2.3 Deck design 5719.2.4 Foundations 5719.2.5 Seismic analysis 5729.3 Structural Health Monitoring 5739.3.1 Equipment 5739.4 Snow and Ice Removal and Prevention Systems 5759.4.1 Mechanical removal 5759.4.2 Thermal systems 5779.4.3 Passive protection 577References 579Index 587