Safety levels of the traditional strength design of RC slabs under bending and torsion

This paper studies the behavior of two RC slabs subjected to bending and torsion, presenting deformation with positive gauss curvature. Special attention is paid to the available methods for the strength design of RC slabs, and to the verification of the assumptions used in these methodologies. Ultimate behavior according to two strength design methodologies has been studied. In order to verify the yielding of the reinforcement at ultimate state assumed in the Brondum-Nielsen method, the experimental and theoretical load-deformation response (monotonic loading) has been obtained. The theoretical response has been studied using both FEM and a Compression Field approach which uses an embedded bar model based on a tension stiffening formulation. A full discussion of these methods according to two detailed tests is described. In order to achieve this, a new testing apparatus has been constructed. The conclusions obtained increase our knowledge about the safety levels of traditional strength design methods for reinforcing concrete slabs.