Automatic Yield-Line Analysis of Practical Slab Configurations via Discontinuity Layout Optimization

The yield-line method provides a powerful means of rapidly estimating the ultimate load that can be carried by a reinforced concrete slab. The method can reveal hidden reserves of strength in existing slabs and can lead to highly economic slabs when used in design. Originally conceived before the widespread availability of computers, the yield-line method subsequently proved difficult to computerize, limiting its appeal in recent years. However, it was recently demonstrated that the discontinuity layout optimization (DLO) procedure could be used to systematically automate the method, and various isotropically reinforced, uniformly loaded slab examples were used to demonstrate this. The main purpose of this paper is to demonstrate that the DLO procedure can also be applied to a wide range of more practical slab problems, for example involving orthotropic reinforcement, internal columns, and point, line, and patch loads. The efficacy of the procedure is demonstrated via application to a variety of example problems from the literature; for all problems considered solutions are presented that improve upon existing numerical solutions. Furthermore, in a number of cases, solutions derived using previously proposed automated yield-line analysis procedures are shown to be highly nonconservative.