The Critical Load of Trusses with Redundant Members

Mr. F. Turton (Member) said that he was interested in the history of these bridges. In the Lune Bridge they had an excellent example of a problem which the bridge engineers concerned had at some time or another met in three different ways. The designer of the original bridge had decided to use framed arches in timber; what his reasons had been they did not know but it seemed a rather elegant solution to a problem quite different from the one met on the present occasion, since the original designer had not had to deal with railway traffic. He had probably had to allow for river traffic from the harbour which then existed at Lancaster, upstream of the bridge, and for the passage of sailing vessels, or possibly steam vessels, with tall masts.

Opening the discussion, the President asked if Mr. Evans could say something further regarding costs. For example, what was the approximate cost per seat of all the seats under the canopy?

The paper describes large deflexions found in electrically floor heated reinforced concrete slabs in a considerable number of Scottish flats and gives the basic reasons why such deflexions occur. It goes on to describe a number of laboratory tests to ascertain the shrinkage of the aggregates used for constructing the floors and the influence on concrete made with such aggregates and similar sands. The results of E tests are given. An investigation into the temperature and deflexion characteristics with or without live load of a typical flat is described and the results are given, together with examples of deflexion readings from other flats and core crushing results. R.A. Sefton Jenkins, J.M. Plowman and B.A. Haseltine