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Transcriber's Notes:

Text between underscores represents _italics_, small capitals have been
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  THE
  ANATOMY OF BRIDGEWORK




  THE
  ANATOMY OF BRIDGEWORK

  BY

  WILLIAM HENRY THORPE
  ASSOC. M. INST. C. E.

  WITH 103 ILLUSTRATIONS

  [Illustration]

  London
  E. & F. N. SPON, LIMITED, 57 HAYMARKET
  New York
  SPON & CHAMBERLAIN, 123 LIBERTY STREET

  1906




PREFACE


In offering this little book to the reader interested in Bridgework, the
author desires to express his acknowledgments to the proprietors of
"Engineering," in which journal the papers first appeared, for their
courtesy in facilitating the production in book form.

It may possibly happen that the scanning of these pages will induce
others to observe and collect information extending our knowledge of
this subject--information which, while familiar to maintenance engineers
of experience, has not been so readily available as is desirable.

No theory which fails to stand the test of practical working can
maintain its claims to regard; the study of the behaviour of old work
has, therefore, a high educational value, and tends to the occasional
correction of views which might otherwise be complacently retained.

  60 WINSHAM STREET,
  CLAPHAM COMMON, LONDON, S.W.
  _October_, 1906.




CONTENTS


  CHAPTER I.

  INTRODUCTION--GIRDER BEARINGS.

                                                                    PAGE

  Pressure distribution--Square and skew bearings--Fixed bearings--
  Knuckles--Rollers--Yield of supports                                 1


  CHAPTER II.

  MAIN GIRDERS.

  _Plate webs_: Improper loading of flanges--Twisting of girders--
  Remedial measures--Cracks in webs--Stiffening of webs--[T]
  stiffeners                                                           9

  _Open webs_: Common faults--Top booms--Buckling of bottom booms--
  Counterbracing--Flat members                                        17


  CHAPTER III.

  BRIDGE FLOORS.

  Liability to defects--Impact--Ends of cross and longitudinal
  girders--Awkward riveting--Fixed ends to cross girders--Plated
  floor--Liberal depths desirable--Type connections--Effect of "skew"
  on floor--Water-tightness--Drainage--Timber floors--Jack arches--
  Corrugated sheeting--Ballast--Rail joints--Effect of main girders
  on floors                                                           20


  CHAPTER IV.

  BRACING.

  Effect of bracing on girders--Influence of skew on bracing--Flat
  bars--Overhead girders--Main girders stiffened from floor--
  Stiffening of light girders--Incomplete bracing--Tall piers--Sea
  piers                                                               34


  CHAPTER V.

  RIVETED CONNECTIONS.

  Latitude in practice--Laboratory experiments--Care in considering
  practical instances--Main girder web rivets--Lattice girders
  investigated--Rivets in small girders--Faulty bridge floor--
  Stresses in rivets--Cross girder connections--Tension in rivets--
  Defective rivets--Loose rivets--Table of actual rivet stresses--
  Bearing pressure--Permissible stresses--Proposed table--Immunity of
  road bridges from loose rivets--Rivet spacing                       45


  CHAPTER VI.

  HIGH STRESS.

  Elastic limit--Care in calculation--Impact--Examples of high stress
  --Early examples of high stress in steel girders--Tabulated
  examples--General remarks                                           61


  CHAPTER VII.

  DEFORMATIONS.

  Various kinds--Flexing of girder flanges--Examples--Settlement
  deformations--Creeping--Temperature changes--Local distortions--
  Imperfect workmanship--Deformation of cast-iron arches              73


  CHAPTER VIII.

  DEFLECTIONS.

  Differences as between new work and old--Influence of booms and web
  structure on deflection--Yield of rivets and stiffness of
  connections--Working formulae--Set--Effect of floor system--
  Deflection diagrams--Loads quickly applied--"Drop" loads--Flexible
  girders--Measuring deflections--New method of observing deflections
  --Effect of running load                                            85


  CHAPTER IX.

  DECAY AND PAINTING.

  Examples of rusting of wrought-iron girders--Girder over sea-water
  --Rate of rusting--Steelwork--Precautions--Red-lead--Repainting--
  Scraping--Girders built into masonry--Cast iron--Effect of sea-
  water on cast iron--Examples--Tabulated observations--Percentage of
  submersion--Quality of metal                                        96


  CHAPTER