Prestress Analysis for Continuous Beams: Some Developments in the Equivalent Load Method

An integrated form of yield line method incorporating finite elements and linear programming is developed and applied to some illustrative problems. The method is simple to operate and provides an upper bound to the collapse load of the continuous slab. The method is a further example of a significant trend towards the solution of problems of engineering plasticity by mathematical programming. J. Munro and A.M.A. Da Fonseca

The design method for composite frames of steel and concrete given in Part 5 of the Bridge Code uses effective column lengths based on elastic theory, which is strictly not applicable at ultimate loads. Details are given of tests on eight composite columns, elastically restrained about one or both axes, in a purpose-designed rig of capacity 2MN, in which axial load is applied through crossed knife-edges. The ultimate loads, deflections and end moments were found to agree well with computed values. The design method of BS 5400: Part 5 is shown to be satisfactory for these columns, for both the serviceability and the ultimate limit states. R.P. Johnson and I.M. May