Movable Bridge Design

Transcription

1 ice Movable Bridge Design publishing, William Bowden and George A Foerster

2 Contents Preface Acknowledgements About the authors About the contributors Notation xi xiii xv xvii xix 01 Introduction Need for movable bridges Basic motions of movable spans Early movable bridges Notable 19th-century movable bridges 9 References Individual movable span forms Introduction Simple trunnion bascules Balance beam bascules Strauss articulated bascule bridges Rolling bascules (Scherzer) Swing bridges Vertical lift bridges 51 References Movable spans in series Introduction Symbols and notation Double-leaf bascule bridges Mid-span shear locks Double-leaf trunnion girder bascule bridges Double-leaf trunnion bascule bridge examples Double-leaf rolling bascule bridges Tandem swing bridges 79 References Other movable bridge forms Introduction Market Street Bridge, Chattanooga, TN Armstrong swing bridges Movable bridges supported by pontoons Transporter bridges The Bellmouth passage bridges Gateshead Millennium Bridge Belidor bascules Folding bridges Other movable bridge forms 112 References 112

3 05 Movable bridge design standards Introduction Units Development of movable bridge design practice European movable bridge specifications USA Railroad Bridge Safety Standard 120 References Materials of construction Introduction Ferrous materials Wrought iron Steels Heat treatment of steel general Heat treatment of steel gears Cast steel Hot-rolled steel and hot forging Cold-finished steel Cast iron Non-ferrous metals Non-metallic materials Wire rope 143 References Material properties and failure Introduction Material specifications Tensile properties Material hardness Fracture of metals Residual stresses Corrosion Stress corrosion cracking Hydrogen embrittlement Tribology 177 References Span drive arrangements 181 Robert J Tosolt 8.0. Introduction The simple trunnion bascule The rolling bascule The heel trunnion bascule The Hopkins trunnion bascule The swing span The span drive vertical lift bridge 191 vi

4 general 8.7. The tower drive vertical lift bridge 194 References 197 Machinery components 199 George A Foerster 9.0. Introduction Shafts, couplings and universal joints Bearings and bushings Drums and sheaves Linkages Power screws, mechanical jacks and pulling devices Clutches and torque limiters Gears, racks and differentials Parallel shaft, right angle and planetary speed enclosed gear box reducers Roller chains and sprockets Keys, pins, retainer rings, shrink fit devices, collars and threaded fasteners O-rings, lip seals and packing material Springs Closing 217 summary References 217 Stabilisation machinery 219 George A Foerster Introduction Bascule bridges Swing bridges Vertical lift bridges 225 References 229 Superstructure structural design Introduction Common movable bridge superstructure forms Bridge decks Bascule bridges Swing bridges Vertical lift bridges Movable bridge balancing 248 References 251 Mechanical design 255 George A Foerster Introduction Design methods, loadings and load factors Machinery component design Main machinery support components for movable bridges Design of shafts Design of plain and anti-friction bearings 271 vii

5 12.6. Contact stresses and design of rollers Selection of wire rope, drums and sheaves Linkage design Lock bar design Wedge design Selection and design of drive machinery for lock bars and wedges Selection of shaft couplings Interference fits, key and mechanical friction locking devices Brake selection Bolts Welding General gearing Machinery inspection and maintenance Other machinery design considerations Summary 294 References 294 Gearing and speed reducer design 297 Robert L Cragg and Robert J Tosolt Introduction Symbols and abbreviations Gear design Inspection fundamentals Gear design considerations Future considerations 323 References 323 Hydraulic span drive systems 325 James M Phillips III Introduction Hydraulic system fundamentals Hydraulic system components Heating and cooling of hydraulic systems Reserve power factor Hydraulic movable bridge drive types Open-loop hydraulic cylinder bridge drives with proportional directional control Open-loop hydraulic cylinder drives with pump control Hydraulic motor drives Design loads for machinery Design loads for structure Synchronising or load sharing in hydraulic systems Design example 362 References 369 Electrical system design 371 William Bowden Introduction Prime mover 372

6 15.2. AC thyristor drives Flux vector drives and motors Power synchro unit (synchro-tie) Auxiliary motors Brakes Limit switches and resolvers Traffic control devices Electrical power distribution Control system hardware Remote controls Interlocking Bypass switches Documentation Spare parts Testing 393 References 393 Index 395 NB: British English has been used throughout this book, but occasionally readers will find non-british terms where US case studies and examples have been cited. ix