The Theory of Strains in Girders and Similar Structures: With Observations of the Application of Theory to Practice, and Tables of the Strength and Other Properties of Materials

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D. Van Nostrand, 1873 - 632 páginas
 

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CHAPTER II
11
Horizontal strains in braced or thin continuous webs may be neglected
12
FLANGED SEMIGIRDER LOADED AT THE EXTREMITY 16 FlangesAt any cross section the horizontal components of strain in the flanges are eq...
13
Girder of greatest strengthAreas of horizontal flanges should be to each other in the inverse ratio of their ultimate unitstrains
15
girders with parallel flanges is theoretically independent of the depth
16
Depth of semigirder of uniform strength when the flangearea is constant
18
WebShearingstrain
19
Single fixed load flangearea of girder of uniform strength when the depth
25
uniformly distributed 46 Web shearingstrain
35
Flangearea of girder of uniform strength when the depth is constant
36
Depth of girder of uniform strength when the flangearea is constant
37
FLANGED GIRDER SUPPORTED AT BOTH ENDS AND TRAVERSED BY A TRAIN OF UNIFORM DENSITY 50 Passing train of uniform densit...
38
Maximum strains in web occur at one end of a passing train
39
Uniform load and passing train shearingstrain
40
Flanges
41
Depth and length for calculation
42
CHAPTER III
43
Neutral axis Centres of strainResultant of horizontal forces in any cross section equals cipher
44
Moment of resistance MBending moment
45
Coefficient of rupture SSemigirder loaded at the extremity 61 Semigirder loaded uniformly 62 Girder supported at both ends and loaded at an int...
47
Strength of stones even of the same kind is very variable
51
Strength of similar girdersLimit of length
53
Neutral axis passes through the centre of gravityPractical method of finding the centre of gravity
54
GIRDERS OF VARIOUS SECTIONS 69 Moment of resistance M
56
for sections symmetrically disposed above and below the centre of gravity
57
Solid square semigirders with one diagonal verticalSolid square girders
64
Square tubes with vertical sides
70
ART PAGE 103 Solid round semigirder of uniform strength
72
SEMIGIRDERS LOADED UNIFORMLY 106 Solid rectangular semigirders
73
Solid round semigirders
74
Elevation of solid rectangular semigirder of uniform strength breadth constant 112 Solid round semigirder of uniform strength 113 Hollow round...
75
GIRDERS SUPPORTED AT BOTH ENDS AND LOADED AT AN INTERMEDIATE POINT 115 Solid rectangular girders
76
Solid round girders
77
Plan of solid rectangular girder of uniform strength depth constant 120 Elevation of solid rectangular girder of uniform strength breadth constant 12...
79
Concentrated rolling load plan of solid rectangular girder of uniform strength when the depth is constantElevation of same when the breadth is const...
80
Plan of solid rectangular girder of uniform strength when the depth is constant
83
Elevation of solid rectangular girder of uniform strength when the breadth is constant
84
Transverse strength of thick castings much less than that of thin castings
86
Definitions
88
Lattice web has no theoretic advantage over a single systemPractical
94
Flangestrains derived from a diagram
100
Elevation of solid rectangular semigirder of uniform strength breadth
102
Maximum strains in webStrains in intersecting diagonals
106
WebFlanges
112
Web second method
118
GIRDERS SUPPORTED AT BOTH ENDS AND LOADED UNIFORMLY
124
Example 2Flangestrains nearly uniform with symmetric loading
142
Inverted bowstring or fishbellied girderBow and invert or double bow
149
Flanges
157
CHAPTER VIII
164
Central deflection of a girder loaded uniformly equals fiveeighths of
178
Practical method of fixing the points of inflexionEconomical position
185
ART PAGE
187
Three spans loaded uniformly
193
CHAPTER X
200
GIRDERS SUPPORTED AT BOTH ENDS AND LOADED UNIFORMLY
203
Web first method
211
CHAPTER XII
212
Each bay of a braced pillar resembles a pillar with rounded endsCom
286
Prolonged fusion within certain limits increases the strength and density
292
IRON WIRE
309
compared with drilling greatly reduces the tensile strength of steel plates
316
Tensile strength of Keenes Parian and Medina cements
333
Strength and weight of cordageEnglish ruleFrench rule
340
Long openlink chainAdmiralty proofstrainTrinity proofstrain
346
Tensile strength of flat iron and steel wire ropes and flat hemp rope
353
Shearing strength of wroughtiron equals its tensile strength
360
Hodgkinsons formulæ for the increment of length and set of castiron
370
Elastic flexibility of castiron twice that of wroughtironLaw of elasticity
379
ART PAGE
384
A change of temperature of 15 C in castiron and 75 C in wroughtiron
390
Punching and drilling tools
396
CHAPTER XXII
411
Rail girders or keelsons Economical distance between the crossgirders
417
CHAPTER XXIV
424
ART PAGE
426
Effect of centrifugal force
433
CHAPTER XXVII
442
CoversSingle and double covers compared Lapjoint
449
Adhesion of iron and copper bolts to woodStrength of clenches
458
CHAPTER XXVIII
466
Working strain of cast iron girdersRule of Board of TradeWorking
473
Net area only available for tensionAllowance for the weakening effect
482
Examples of working strain in wroughtiron girder and suspension bridges
488
English American and French practicePermanent working strain
495
WORKING LOAD ON RAILWAYS
503
Standard working loads for railway bridges of various spans
510
Weight of roofing materials and working loads on roofsWeight of snow
517
CHAPTER XXIX
525
EXAMPLE 4
533
Great economy from high unitstrains in large girders
540
Great economy from high unitstrains in very large girders
546
GIRDERS UNDER 200 FEET IN LENGTH
552
ART PAGE 521 Andersons ruleWeights of lattice and plate girders under 200 feet in length
553
Weights of similar girders under 200 feet span vary nearly as the squares of their lengthsNo definite ratio exists between the lengths and weights of v...
557
CHAPTER XXX
558
CHAPTER XXXI
561
Strains in ships
563
Iron and timber combined form a cheap girderTimber should be used in large pieces not cut up into planksSimplicity of design most desirable in gir...
564
APPENDIX work
567
361
569
Boyne Lattice Bridge general description and detailed weights of girder 529 Working strains and area of flanges
571
Points of inflexionPressure on points of support
572
Maximum strains in the fanges of the centre span
573
Points of inflexion fixed practicallyDeflectionCamber
574
Experiments on the strength of braced pillars
577
Experiments on the effect of slow and quick trains on deflection
581
Newark Dyke Bridge Warrens Girder
582
Chepstow Bridge Gigantic Truss
583
Crumlin Viaduct Warrens Girder
584
Public Bridge over the Boyne Lattice Girder 58 5
585
Bowstring Bridge on the Caledonian Railway
587
Conway Plate Tubular Bridge
588
Brotherton Plate Tubular Bridge
591
Vitreous materials take no set
627

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Página 470 - The magnitude of the blow in each set of experiments being made greater or smaller, as occasion required. The general result obtained was, that when the blow was powerful enough to bend the bars through one-half of their ultimate deflection (that is to say, the deflection which corresponds to their fracture by dead pressure), no bar was able to stand 4000 of such blows in succession ; but all the bars (when sound) resisted the effects of 4000 blows, etch bending them through one-third of their ultimate...
Página 472 - In wrought-iron bars no very perceptible effect was produced by 10,000 successive deflections by means of a revolving cam, each deflection being due to half the weight which, when applied statically, produced a large permanent flexure.
Página 250 - A long, uniform, cast-iron pillar, with its ends firmly fixed, whether by means of discs or otherwise, has the same power to resist breaking as a pillar of the same diameter, and half the length, with the ends rounded or turned so that the force would pass through the axis.
Página 249 - The strength of a pillar, with one end rounded and the other flat, is the arithmetical mean between that of a pillar of the same dimensions with both ends round, and one with both ends flat. Thus, of three cylindrical pillars, all of the same length...
Página 306 - In screwed bolts the breaking strain is found to be greater when old dies are used in then- formation than when the dies are new, owing to the iron becoming harder by the greater pressure required in forming the screw thread when the dies are old and blunt than when new and sharp.
Página 249 - Thus, of three cylindrical pillars, all of the same length and diameter, the first having both its ends rounded, the second with one end rounded and one flat, and the third with both ends flat, the strengths are as 1, 2, 3, nearly.
Página 470 - A heavy ball was suspended by a wire eighteen feet long from the roof, so as to touch the centre of the side of the bar. By drawing this ball out of the vertical position at right angles to the length of the bar, in the manner of a pendulum, to any required distance, and suddenly releasing it, it could be made to strike a horizontal blow upon the bar; the magnitude of which could be regulated at pleasure, either by varying the size of the ball or the distance from which it was released.
Página 431 - Ibs. is sufficient to produce fracture if passed over them at the rate of 30 miles an hour. It also appeared that when motion was given to the load, the points of greatest deflection, and, still more, of the greatest strains, did not remain in the centre of the bars, but were removed nearer to the remote extremity of the bar. The bars, when broken by a travelling load, were always fractured at points beyond their centres, and often broken into four or five pieces, thus indicating the great and unusual...
Página 483 - In a wrought-iron or steel bridge the greatest load which can be brought upon it, added to the weight of the super-structure, should not produce a greater strain on any part of the material than five tons, where wrought-iron is used, or six tons and a half, where steel is employed, per square inch.
Página 361 - ... for copper plates. Multiply the constant number by the given diameter in inches, and by the thickness in inches ; the product is the pressure in pounds, which will be required to punch a hole of a given diameter, through a plate of a given thickness. It was observed that, duration of pressure lessened considerably the ultimate force necessary to punch through metal, and that the use of oil on the punch reduced the pressure about eight per cent. A drawing of the experimental lever and apparatus...

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