Discrete elements in structural concrete design

In the sixties Prof. J. Witteveen introduced a discrete model for the elastic analysis of slabs (Heron 1966). This article presents a similar approach for the design of reinforced concrete walls and deep beams, with holes or otherwise. The model – which is called stringer-panel model – combines the advantages of the popular strut-and-tie method and the standard finite element method. It has the same geometry as the plastic model proposed by Prof. M.P. Nielsen in the seventies (Kaern 1979). However, the stringer-panel model accurately uses the non-linear behaviour of reinforced concrete. So, it encompasses both the elastic and plastic states. The method provides crack width information in the serviceability limit state and allows for redistribution of forces in the ultimate limit state. A design example shows the usability of the model in engineering practice.