The yield-line method for concrete slabs: automated at last

The yield-line method of analysis provides a powerful means of identifying the ultimate load-carrying capacity of reinforced concrete slabs. Benefits of the yield-line method are that it will often identify additional reserves of strength when applied to the analysis of existing slabs, and to highly economic slabs when used in design. Traditionally a hand-based method, the yield-line method is easy to apply to problems involving simple slab geometries and loading regimes. However, when these become more complex it can be difficult to identify the critical yield-line pattern.
To address this, the method has now been systematically automated. The automated method quickly identifies the critical mechanism (or a close approximation of this) and corresponding load-carrying capacity, providing engineers with a powerful new computer-based tool for the analysis and design of concrete slabs. In this article, the discontinuity layout optimisation (DLO) procedure which has been used to automate the yield-line method is briefly described and then applied to various example problems.