E Sherman GouldRelease Date: 16 December 2009
Format: Paperback / softback
Pages: 94
ISBN: 9781117766492
ISBN-10: 1117766497
HIGH MASONRY DAMS - 1897 -TABLE OF CONTENTS. PREFACE ............................................... 3 I . CHAPTER I. STATICST RESSE . S .. . . . . ........... 7 CHAPTER 11.-UNIT STRES .. S .. .................. 19 CHAPTER 111. - UNEQUALLY DISTRIBUTED UNIT STRESS .. . . . . ................................. 31 CHAPTER 1V.-THE VERTICAL S ECTION OF HIGHM ASONR Y X hl . s .. ....................... 41 CHAPTER V. T H E C ONSTRUCTIO O N F HIGH CHAPTER VI.-ACCESSORIE O S F DAMS . . . .... 77 - THE present voluner eplaces the original No. 22 of Van Nostrands Science Series, bearing the same title, by Mr. John B. McMaster. Mr. RfcMasters volume treated mainly of the mathematical calculation of high lna. sollry dams as it was uilderstood at the time. at whicich he wrote. Since then. the masterly treatise of 1 1 E d . w ard Wegmann, upon the same subject, has so completely superseded all other treatment of the mathematical features involved that it would be useless to revive old methods. Besides, the present autl or has lbng been collvillcsd of the fact that, in view of the many practical limitations which surround the design of a high masonry dam, it is useless to attempt to adhere to a general formula for that great . desiderk turn of all economical engineering design -namely, a - SECTION OF EQUAL RESISTANCE. The mathematical researches of those authors who have investigated this problem have estlablished a vertical section, the basis of which is a right-angled triangle of . b, a se equal to two-thirds or three-quarters of its height, as that leading to, qrat C least looking towards, such a result. The most refined calculations will inevitably beng us back to the neighborhood of this forin forat least the first hundred or two hundred feet of any proposed dam, the difference of relation between the base and height of the triangle depending mainly upon the limiting unit stress adopted. We cannot do better, therefore, than t, o profit by, rather than to repeat, the labors of those distinguished mathematicians and engineers who have been our pioneers in this work, and start our designs by first lay ing down such a triangle, surmounting it by a proper practical top width instead of its own sharp apex, and, if its height exceeds SO to 100 feet, giving a flare to the lower part of its inside face to expand the footing on that side.. Then, by simple and well-known processes, we determine the maximum a . l t t . t 1 t i compressive, stress upon the maternal at certain d . i I f ferent heights, upon the two assumptions of an empty and a full reservoir, and if they do not prove satis f, A c - tory, modify the section accordingly, subordina tin . g t he modifications . I to certain practical conditions . previously . A ., . . de termined upon. I sill be seen that the dangerous stress in a very highmasonry dam is the t crushin . g o, ne. he author, has enfleavored d to, treat he question of this stress quite fully, begi nding with its onsideration when uniformly distributed, r . and i, showing. the manner in which, theoreticql-i t ly, a structure can be proportioned so as to render this stress uniform, no matter l . to what height it may be raised. In this p . way the rapid increaso of base, after a certain height has been reached, necessary to secure t. his uniformity of pressure, is clearly shown, indicating that. there is a practical limit tothe height to which thYe structure can beraised. The investigation then passes to the consideration of . maximum unit stresses when the resultant of pressures cuts the base unsyrnrnet i2 cally, as is the case in dams...
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