JOHN WILEY & SONS PUBLISH, By the same Author, THE STRAINS IN FRAMED STRUCTURES, with numerous practical applications to Cranes, Bridge, Roof and Suspension Trusses, Braced Arches, Pivot and Draw Spans, Continuous Girders, etc.; also Determination of Dimensions and Designing of Details, Specifications and Contracts. Complete Designs and WORKING DRAWINGS. By Prof. A. J. Du Bois. Illustrated with hundreds of Cuts and 35 Full-page and 15 Folding Plates. 1 vol., 4to, cloth, $10 00 From C. S. MAURICE, Supt. Kellogg & Maurice Bridge Co. "I must congratulate you on having produced the best treatise on the subject that has yet appeared." From CHAS. M. JARVIS, Supt. Berlin Iron Bridge Co. "The most practical work of the kind we have ever seen." TABLES FOR BRIDGE ENGINEERS, showing at a glance the Maximum Shear and Maximum Moment at any point of a span from 10 to 300 feet, as well as the position of the Load System and what wheel of the Locomotive is over the point in question, saving an enormous amount of labor to the Engineer, and giving exact and reliable results. By Prof. A. J. Du Bois. 50 pages, all Tabular Work.. ......1 vol., 4to, HYDRAULICS AND HYDRAULIC MOTORS. With numerous practical examples for the calculation and construction of Water Wheels, including Breast, Undershot, Back-pitch, Overshot Wheels, etc., as well as a special discussion of the various forms of Turbines, translated from the fourth edition of Weisbach's Mechanics. By Prof. A. J. Du Bois. Profusely illustrated. Second edition.... 8vo, cloth, 5 00 THEORY OF THE STEAM ENGINE. Translated from the fourth edition of Weisbach's Mechanics, by Prof. A. J. Du Bois. Containing notes giving practical examples of Stationary, Marine, and Locomotive Engines, showing American practice. By R. H. Buel. Numerous illustrations. ... 1 25 8vo, cloth, 5 00 THERMO-DYNAMICS, THE PRINCIPLES OF. With Special Applications to Hot Air, Gas, and Steam Engines. By Robert Röntgen. With additions from Profs. Verdet, Zeuner, and Pernolet. Translated, revised, and enlarged by Prof. A. J. Du Bois, of Sheffield Scientific School. 670 pages.... .8vo, cloth, 5 00 THE CALCULATIONS OF STRENGTH AND DIMENSIONS OF IRON AND STEEL CONSTRUCTIONS. With reference to the latest experiments. By Prof. J. J. Weyrauch, Polytechnic Institute of Stuttgart. Translated by A. J. Du Bois. With Plates.... ...8vo, cloth, 1 50 IN FRAMED STRUCTURES, WITH NUMEROUS PRACTICAL APPLICATIONS ΤΟ CRANES-BRIDGE, ROOF AND SUSPENSION TRUSSES-BRACED ARCHES ALSO, PETERMINATION OF DIMENSIONS AND DESIGNING OF DETAILS-SPECIFICATIONS AND CONTRACTS-COMPLETE DESIGNS AND WORKING DRAWINGS. BY A. JAY DU BOIS, C.E., Ph.D., PROFESSOR OF CIVIL ENGINEERING IN THE SHEFFIELD SCIENTIFIC SCHOOL OF YALE ་་ OF AMERICAN SOCIETY OF MECHANICAL ENGINEERS; AMERICAN TUTE OF MINING ENGINEERS, ETC, FIFTH EDITION, REVISED AND GREATLY ENLARGED. NEW YORK: JOHN WILEY & SONS. 1890. PREFACE. To those who make use of this work, whether teacher or student, a few words as to its plan may be of service. The work is divided into two PARTS. PART I. consists of two SECTIONS. SECTION I. gives, in four short chapters, the principles which lie at the bottom of all methods of calculation. In these chapters all unnecessary detail has been avoided, the object being to familiarize the student first with the fundamental principles. Each chapter contains the ground-work of a separate method of calculation, and the same illustrative example is used in each. The student who has thus familiarized himself with the four fundamental methods of calculation, can afterwards combine these methods in the solution of any particular case, as may seem best. It is believed that every method in use will be found on analysis to be a combination of two or more of the methods set forth in these first four chapters, and, so far as known to the writer, the present work is the only one in which such division has been made, and each method given clearly by itself independently of the others, In SECTION II. the application of these methods to the solution of various structures is given with all necessary detail. It has been the aim of the writer to make this section very complete in full solutions of every existing form of bridge. The student, already familiar with the four fundamental methods, is now in no danger of being confused by detail, and can easily devise for himself other methods of solution for individual cases, as good, or even better, than those given. In Chapter I. of this section will be found a more complete treatment of Roof Trusses than has been thus far given in any work known to the writer. In Chapters III. and IV. a simple bridge girder is taken, and calculated fully, first by each of our four fundamental methods, and lastly by that combination of methods which seems best adapted to the case in hand. The remainder of the section gives the complete calculation of every form of bridge known, each case illustrated by an example carefully worked out. In Chapters VI. to VIII. upon the continuous girder, pivot or swing bridge and braced arch, much new matter will be found, and it is thought that the methods given will commend themselves as practical and easy of application. Whatever may be thought of the comparative advantages or disadvantages of these forms of bridges, they cannot well be omitted from a work which aims at any degree of completeness. For the average student, perhaps, so full a course is not desirable, at least at first, and therefore the attempt has been made by means of finer print to mark out two courses of study. In any case the intelligent teacher will know what to omit, and it is no disadvantage to a student to be possessed of a Text Book which includes more than he has been able to read, and which may, therefore, be of future benefit instead of being laid on the shelf when finished. In Chapter IX. the suspension system is given at considerable length, perhaps more than its importance demands. The entire chapter is believed to be new, and so far as the writer knows, it is the only solution of this construction which is free from assumptions known to be false.* It is, therefore, given here for what it is worth as a contribution to the science of Bridge Calculation. In the Supplement to Chapter IX. the ordinary theory is also given with all requisite fulness. Everywhere it has been the aim of the writer to keep mathematical demonstrations out of the body of the work, so far as possible to do so. In the APPENDIX to PART I. will be found, in connected form, all the mathematical deductions referred to and made use of in the Text. The chapter upon the Theory of Flexure is especially full, and in that upon the Continuous Girder new matter will be found. The mere calculation of strains alone is but one part of the general problem of design, and by no means the most important. It is quite as necessary to properly proportion a structure for the stresses it has to sustain, as to know beforehand what these stresses are. In PART II., therefore, will be found as full a treatment of the important topics of cross-sectioning and designing of details and connections as the writer has been able to give. That practical bridge builders will find here much to criticize, goes without saying. The writer will be glad of any and all such criticisms, and will avail himself of them in the improvement of this very important part of the work. He can only ask for the present attempt the indulgence which, perhaps, it can claim, as among the first in a work of this character to combine "practice" with "theory," and hopes that portions of it may not be without interest and value even to the practical engineer. NEW HAVEN, June, 1883. * Since writing the above, I have learned that precisely the same method of discussion was first applied by Charles Bender, C. E., and published in Van Nostrand's Engineering Magazine for November, 1881. It will also be found, extended in treatment, in "Principles of Economy in the Design of Metallic Bridges," by the same author (Wiley & Sons). |