Recent Developments in the Design of Submerged Tunnels

The paper presents a numerical technique based on improved finite differencc formulae of the Hermitian type, for the analysis of structures taking into account the second-order effects of the displacements of the structure. The same method can be extended to evaluate the critical loads of structures. The method, which is quite general, does not make use of previously tabulated data and can also include non-linear effects in the analysis. It can be applied to the second-order analysis of most plane structures including continuous beam-columns, multi-storeyed rigid frames and arches. The author has illustrated the approach with several applications. B.N. Thadani

The initial choice of layout parameters determines to a large extent the overall cost of bridge structures. This initial choice, however, is itself dependent upon the relative unit costs of the materials employed. E.M. Aziz and A.D. Edwards

A conventional method of analysis and design for trough-shaped bunkers is explained. A full-scale test on a large coal bunker is described and the experimental coal pressures and the stresses in the steelwork are compared with design values. Further measurements from a similar model in aluminium are reported. It is shown that theoretical strcsses can be brought into line with measured stresses if the plating is assumed to act with the stringers and, to some extent, with the main and the base girders; such assumed composite action might well be the basis for future design recommendations. E. Lightfoot and D. Michael