Circular ring-shaped plate loaded by tangential forces and by isolated point force

This paper reports on loading tests made on a pair of prestressed steel girders designed for use in an elevated roadway scheme in London. The consulting engineers were engaged in preparing a report comparing various forms of construction before recommending the most suitable scheme to the clients, and the tsets were carried out as part of this investigation. E. V. FINN and F. H. NEEDHAM

The stresses and deflexions in a castellated girder are calculated by the simple theory of bending and by two methods in which it is assumed that the girder behaves as a Vierendeel truss. The calculated values are compared with experimental data and it is shown that the simple theory of bending usually underestimates deflexions by 20 to 30 per cent and that the measured stresses at some points in the girder deviate appreciably from the calculated values. However, the Vierendeel truss analogy is shown to provide more reliable values. J. KOLOSOWSKI

Mr. A. Jennings, Lecturer in the Civil Engineering Department of the University of Manchester, writes: ‘The standard methods of solution of linear redundant structures are all formulated in terms either of the unknown forces or of the unknown displacements and use the flexibility or stiffness properties of the structure to effect a solution. The method of solution of free cable problems advocated in this paper is peculiar in that it does not formulate the analysis directly in terms of either the unknown displacements or the unknown forces, and no concept of stiffness or flexibility is introduced.