, said that the Author had been Dfr. Harrison good enough to give an account of the substructure of the Tower Bridge. He trusted that when the bridge was finished the Author would also give an account of the superstructure. The bridge was original both in conception and in design and it was important that a complete account of it should appear in the Minutes of Proceedings. He had much satisfaction in proposing a vote of thanks to the Author for his useful and practical Paper. cussion of this important Paper, noticed one point to which he should like to refer, viz., the strengthof the toe which was carried all round the foundation at the base of the concrete, for the purpose, he presumed, of increasing the superficial area of the clay on which the bridge stood. He had done such a thing himself and so far as he k:new it had answered very well. He thought, however, that there must be in this case a considerable tensile strain in the base of the concrete at the heel of the toe. The settlement of such a bridge upon the clay tended to take the form of a curved line, and the pressure must, therefore, be very severe upon the toe. H e believed that, unless there was timber or iron in the base (he should be glad to know if there were such), a considerable tensile stress would be thrown upon the concrete at the point he had indicated, tending to crack if not to shear it. the subject of the Tower Bridge at the present stage of its progress, because there was enough detail in this structure for two Papers, one upon the foundations and one upon the superstructure. A bridge must not only be looked upon by itself in elevation, but the circumstances of the site should be duly considered in every case. The circumstances of the present site were that there were important wharves abore the bridge ; and by building a bridge with an open span, those wharves need not be purchased and need not be W) fully compensated. The two river-piers permitted the construction of suitable arrangements for an opening central span ; and it would be seen that, owing to the area required for the pressure on the base, there was room for the counterbalance in the 70-foot width to assist the opening. After all 70
Discussion.&Ir. Woods. Mr. E. WOODS, Vice-President, said that the subject was a most interesting and important one, and he was glad to notice the presence of many eminent manufacturers of steel and others who had occasion to use steel for boilers, steam-engines, ships, bridges, and machinery of various kinds. Amongst the various lines of inquiry which the Author had noticed, he thought attention should be particularly directed to three or four.One was the standard tests which had been adopted to test the quality of steel for various structures, especially as to whether any modifications in them could be properly introduced in view of the most recent experience. Another question was the efficient mode of testing so as to secure uniformity in the results. At present tests were obtained by different classes of machines, and machines in different conditions.It would also be of importance to learn the precautions which had been found necessary in manufacturing steel of different qualities required for different classes of work. Then there was the question of the relative cost of structures, which might be advantageously considered. did not know whether the Author intended to draw any distinction between different qualities of steel. It should always be remembered that a great deal of the steel now manufactured, so far as its chemical constitution was concerned, was rather entitled to the appellation of wrought iron. Some years ago he took part in a Conference a t Philadelphia, in which an endeavour was made to avoid confusion of nomenclature by speaking of steel as either welded or ingot, and of iron as either welded or ingot. Some such distinction required to be borne in mind in speaking of the strength of a material which might differ so much in character and composition. Unfortunately the suggestions then thrown out were not adopted, and the consequence was t,hat engineers were placed in the difficulty of not knowing what was really the article with which they had to deal when speaking of steel or iron. Of course a great deal depended upon price, and the difficulty of introducing steel for certain purposes appeared, according to the Author, to be ascribed to the greater cost. That, however, he believed was a mese question of time. The Author had mentioned the fact that steel rails were made more cheaply than wrought-iron rails, but it had been stated that on the Tees manufacturers could afford to bring iron ore from Spain, a distance of a t least
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.