Automated lower bound analysis of concrete slabs Available to Purchase

A method is developed that allows automated lower bound analyses of concrete slabs to be carried out, with the specific aim of producing a technique that can be applied to existing structures which are being assessed after many years in use and for which the original calculations, and hence the assumed methods of load distribution, have been lost. It is shown that any load distribution within the slab can be expressed in terms of an equilibrium state and a set of states of self-stress. Optimisation techniques are developed that allow the highest lower bound to be found. It is shown that an analysis based on the original Hillerborg two-strip model fails to find a reasonable lower bound when the slab is subjected to point loads and in the corners of slabs but a refinement using four sets of strips at 45° to each other can give very good agreement with both exact analytical solutions and upper bound methods.