A

HANDY BOOK

FOR THE CALCULATION OF

STRAINS IN GIRDERS

AND SIMILAR STRUCTURES, AND THEIR STRENGTH;

CONSISTING OF

FORMULÆ AND CORRESPONDING DIAGRAMS,

WITH

NUMEROUS DETAILS FOR PRACTICAL APPLICATION,

ETC., ETC.

BY WILLIAM HUMBER, Assoc. INST. C.E.

AUTHOR OF "A PRACTICAL TREATISE ON CAST AND WROUGHT IRON

་་

BRIDGE CONSTRUCTION,' A RECORD OF THE PROGRESS

OF MODERN ENGINEERING,"

ETC., ETC.

LONDON:

LOCKWOOD & CO., 7, STATIONERS' HALL COURT.

PREFACE.

NOTWITHSTANDING that the subject of Strains has been ably treated of again and again, it is difficult in submitting this little work to the public to avoid the almost stereotyped expression that "the design has been to supply a want long felt in the profession;" for the numerous volumes which have appeared on the subject have not, principally on account of their elaborate investigations, been calculated to afford that ready assistance which in the ordinary run of office and other work is being continually needed, while on the other hand, most of the general Engineering Pocket-books, not having been able to afford sufficient space to do justice to the subject, have been compelled to leave its treatment incomplete. It is hoped, therefore, that by devoting a small work, in a handy form, entirely to Bridge and Girder Calculations, without giving more than is absolutely necessary for the complete solution of practical problems, both the above obstacles to quick and satisfactory manipulation may be overcome.

One of the chief features of the present work is the extensive application of simply constructed diagrams to the calculation of the strains on bridges and girders, the advantages of which as a system, most undeniably far outweigh its disadvantages. The parabola (anything but a troublesome figure to draw) and a few right lines are all that are required.