Extended sandwich model for reinforced concrete slabs in flexure

In this paper, the description of the flexural behavior of orthogonally reinforced concrete slabs with the newly developed extended sandwich model is presented. On the basis of a sandwich model, the sandwich covers are treated with the cracked membrane model that considers rotating, stress free cracks as well as tension stiffening. Bottom and top cover are coupled by using a compatibility condition. The influence of a deviation of the principal shear and moment direction from the direction of the in-plane reinforcement on the flexural strength is presented and compared with the normal moment yield criterion. Verifications against experimental data generally show a good agreement. Experimental evidence relating to deviations of the principal shear and moment direction from the in-plane reinforcement direction is confirmed.