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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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
19
FLANGED GIRDER SUPPORTED AT BOTH ENDS AND LOADED AT
22
FLANGED GIRDER SUPPORTED AT BOTH ENDS AND LOADED
29
ART PAGE 45 A concentrated load produces the same strain in the flanges as twice the load uniformly distributed
35
Flangearea of girder of uniform strength when the depth is constant
36
Depth of girder of uniform strength when the flangearea is constant
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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
Maximum strain in flanges occur with load all over
41
Depth and length for calculation
42
CHAPTER III
43
Neutral axisCentres of strainResultant of horizontal forces in any cross section equals cipher
44
Moment of resistance M Bending moment
45
Coefficient of rupture SSemigirder loaded at the extremity 61 Semi girder loaded uniformly 62 Girder supported at both ends and loaded at an inter...
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
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CHAPTER IV
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for sections symmetrically disposed above and below the centre of gravity
57
Two classes of Aanged girders
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Hollow round semigirders of uniformn thickness
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ART PAGE 103 Solid round semigirder of uniform strength
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SEMIGIRDERS LOADED UNIFORMLY 106 Solid rectangular semigirders
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Solid round semigirders
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Elevation of solid rectangular semigirder of uniform strength breadth
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GIRDERS SUPPORTED AT BOTH ENDS AND LOADED AT AN INTERMEDIATE POINT 115 Solid rectangular girders
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Solid round girders 117 Hollow round girders of uniform thickness 118 Flanged girders or rectangular tubes taking the web into account
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Plan of solid rectangular girder of uniform strength depth constant 120 Elevation of solid rectangular girder of uniform strength breadth constant 12...
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Concentrated rolling load plan of solid rectangular girder of uniform strength when the depth is constantElevation of same when the breadth is const...
80
GIRDERS SUPPORTED AT BOTH ENDS AND LOADED UNIFORMLY 125 Solid rectangular girders
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Solid round girders 127 Hollow round girders of uniform thickness 128 Flanged girders or rectangular tubes taking the web into account
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Plan of solid rectangular girder of uniform strength when the depth is constant
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Elevation of solid rectangular girder of uniform strength when the breadth is constant
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Transverse strength of thick castings much less than that of thin castings
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Strains in intersecting diagonalsGeneral law of strains in intersecting
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LATTICE GIRDERS SUPPORTED AT BOTH ENDS AND LOADED UNIFORMLY
111
GIRDERS SUPPORTED AT BOTH ENDS AND LOADED UNIFORMLY
124
Ambiguity in the strains of a crescent girder when resting on more than
143
Inverted bowstring or fishbellied girderBow and invert or double bow
149
Flangestrains calculated hy moments
182
Practical method of fixing the points of inflexionEconomical position
185
CONTINUOUS GIRDERS OF THREE SYMMETRICAL SPANS LOADED
191
Strain at centre theoretically onethird and strength theoretically once
197
GIRDERS SUPPORTED AT BOTH ENDS AND LOADED UNIFORMLY
203
+ and H shaped pillars
258
ART PAGE
265
Solid steel pillars
279
Each bay of a braced pillar resembles a pillar with rounded endsCom
286
Prolonged fusion within certain limits increases the strength and density
292
Castiron not suited for tension
296
CRESCENT GIRDER
302
Tensile strength of wroughtiron mean results
303
IRON WIRE
309
Steel plates often deficient in uniformity and toughnessPunching
316
Lateral adhesion of the fibres
324
Tensile strength of Roman cementNatural cements generally inferior
330
Grants conclusions
336
Government Proofstrain for Studchain
342
Working strain of chains should not exceed onehalf the proofstrain
348
CHAPTER XVII
356
Hodgkinsons formulæ for the increment of length and set of castiron
370
Elastic flexibility of castiron twice that of wroughtironLaw of elasticity
379
TEMPERATURE
384
A change of temperature of 15º C in castiron and 7 5 C in wroughtiron
390
Punching and drilling tools
396
Plating more economical than bracing near the ends of very long girders
402
CHAPTER XXII
411
Maximum weight on crossgirdersDistance between crossgirders
417
CHAPTER XXIV
424
CHAPTER VI
426
Effect of centrifugal force
433
CHAPTER XXVII
442
CoversSingle and double covers compared Lapjoint
449
ART PAGE
455
Adhesion of nails and wood screws
462
Effects of longcontinued impact and frequent deflections on castiron bars
470
Working load on castiron pillars
477
Gross area available for compressionCompressive working strain
484
Strength and quality of materials should be stated in specificationsProof
491
ART PAGE
498
Introductory
507
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 3
532
EXAMPLE 5
538
Andersons ruleWeights of lattice and plate girders under 200 feet
553
CHAPTER XXXI
561
APPENDIX
567
Maximum strains in the flanges of the centre span
573
Experiments on the effect of slow and quick trains on deflection
581
Bowstring Bridge on the Caledonian Railway
587

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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 306 - Heated steel by being plunged into oil instead of water is not only considerably hardened but toughened by the treatment. 39. Steel plates hardened in oil and joined together with rivets are fully equal in strength to an unjointed soft plate, or the loss of strength by riveting is more than counterbalanced by the increase in strength by hardening in oil. 40. Steel rivets fully larger in diameter than those used in riveting iron plates of the same thickness being found to be greatly too small for...
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 i - The THEORY of STRAINS in GIRDERS and similar Structures, with Observations on the application of Theory to Practice, and Tables of the Strength and other Properties of Materials. By BINDON B.
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 243 - ... occurred in vertical planes, splitting up the specimen in all directions; cracks were noticed to form some time before the specimen finally gave way ; then these rapidly increased in number, splitting the glass into innumerable irregular prisms of the same height as the cube; finally, these bent or broke, and the pressure, no longer bedded on a firm surface, destroyed the specimen.
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 307 - ... increased. 64. The density of iron is decreased by being drawn out under a tensile strain, instead of increased, as believed by some. 65. The most highly converted steel does not, as some may suppose, possess the greatest density. 66. In cast-steel the density is much greater than in puddled-steel, which is even less than in some of the superior descriptions of wrought-iron. The foregoing extracts afford the reader but a meagre idea of Mr. Kirkaldy's laborious researches, and the student who...
Página 306 - ... water is hardened, and the breaking strain, when gradually applied, increased, but at the same time it is rendered more liable to snap. 44. Iron, like steel, is softened, and the breaking strain reduced, by being heated and allowed to cool slowly. 45. Iron subject to the cold-rolling process hae its breaking strain greatly increased by being made extremely hard, and not by being " consolidated,
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...

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