ABSTRACT
In the mid-nineteenth century, one response to the problem of creating large span structures was the development of the tubular beam. Early beams of this type, for moderate spans, were erected in the 1830s, but it was the construction of large tubes, with spans of over 400 ft (90 m), for the Britannia Bridge that brought this form of structure to the attention of a wider audience. Robert Stephenson and William Fairbairn, designer and detailer of this structure, developed the tubular beam and attempted to have this form of structure used more widely. By 1860, when the Great Victoria Tubular Bridge was opened across the St Lawrence River, in Canada, although many tubular beams had been used, this particular form of beam had fallen out of favour.
This paper discusses the differences between the first and last of these large-span bridges, some of the reasons for the changes in attitudes towards this form of structure; and how these were related to new ideas in structural design generally. An attempt is made to identify the people who questioned the economic viability and efficiency of the tubular beam in the technical press and at institutional meetings, and to offer some reasons why it fell from favour and exerted little influence on the subsequent evolution of large span structures.
