Long-span Railway Bridges (revised Edition); Comprising Investigations Of The Comparative…

Paperback | May 17, 2012

bySir Benjamin Baker

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1873 Excerpt: ...shocks in working, is so powerful, that engineers give up the attempt to confer permanent durability by increased strength, and accept the alternative of a limited life for this special member of the machine. Striking illustrations of this fact are afforded by forge machinery, thus, notwithstanding the enormous weight of metal employed in the construction of squeezers for blooms, the life of the squeezer arm averages but ten months, whilst that of the crank, which revolves at the rate of from 50 to 80 revolutions per minute, is but three months. Mechanical engineers have, therefore, at all times necessarily appreciated the prejudicial action of alternating strains, but the matter has not been enforced in the same manner upon the attention of civil engineers engaged in the construction of bridges. Indeed, until the results of the exhaustive experiments carried out by Herr Wohler were made public, the absence of exact data afforded some excuse to engineers for-the occasional underrating of the effects of repeated strains. No such an excuse can now be legitimately urged, for these experiments conclusively prove that whilst an occasional excessive strain may be risked, a frequently recurring high strain should be guarded against as no less disastrous to the structure in the long run than the imposition of the ultimate strain at once. The higher the unit strain, the shorter will be the life of the material, though not in precise inverse proportion. Thus, in one series of experiments, the bars broke with less than half a million applications of a tensile strain, amounting to about f of the ultimate resistance, whilst when the strain was reduced to about f of the breaking strain, the bars sustained upwards of ten million applications of the load. The essential dif...

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1873 Excerpt: ...shocks in working, is so powerful, that engineers give up the attempt to confer permanent durability by increased strength, and ...

Format:PaperbackDimensions:50 pages, 9.69 × 7.44 × 0.1 inPublished:May 17, 2012Publisher:General Books LLCLanguage:English

The following ISBNs are associated with this title:

ISBN - 10:0217860516

ISBN - 13:9780217860512

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