ON TUBULAR GIRDER BRIDGES. BY WILLIAM FAIRBAIRN, M. INST. C.E. WITH AN ABSTRACT OF THE DISCUSSION UPON THE PAPER. EDITED BY CHARLES MANBY, M. INST. C.E., SECRETARY. EXCERPT MINUTES OF PROCEEDINGS, VOL. IX. OF THE INSTITUTION OF CIVIL ENGINEERS. BY PERMISSION OF THE COUNCIL. LONDON: PRINTED BY W. CLOWES AND SONS, STAMFORD STREET. INSTITUTION OF CIVIL ENGINEERS. March 12, 1850. WILLIAM CUBITT, President, in the Chair. No. 826.-"On Tubular Girder Bridges.' DOUBTS having been entertained as to the ultimate security of the Torksey Bridge, over the River Trent, the Author has investigated the subject with the utmost care and attention. A difference of opinion appears to exist, 1st. As to the application of a given formula† for computing the strength of wrought-iron tubular girders. 2ndly. As to the excess of strength that should be given to a tubular-girder bridge, over the greatest load that can be brought upon it; and, 3rdly. As to the effects of impact, and the best mode of testing the strength, and proving the security, of the bridge. These appear to be the chief points at issue: and, as a reply to both parties by whom he has been consulted, the Author has endeavoured to enunciate such views as will, he trusts, settle the question, and prove satisfactory as to the strength and other properties of these important structures. Previous to entering upon the investigation, it may, however, be requisite to offer a few remarks relative to the construction, and other matters connected with the permanency and security of this description of bridge. *The discussion on this paper extended over portions of several evenings, at different periods, but the abstract of the whole is given consecutively. + Vide page 5. |