Finite Element Analysis of Reinforced Concrete Slabs - Post-test calculations of plate tests using the cracked membrane model

The calculation of the load-deformation behaviour of reinforced concrete slabs, under consideration of the non-linear material behaviour, is an involved and complex process. In this paper post-test calculations of large-scale plate tests are carried out. The utilised constitutive law for reinforced concrete is based on the combination of the cracked membrane model [2] and the layer model according to [4]. The constitutive law was implemented as Usermat in ANSYS MECHANICAL APDL. Comparisons of the calculated and measured load-deformation curves of the plate tests are carried out. The calculated and measured load-deformation curves of the plate tests are compared. Further, for a selected plate test, comparisons are carried out for the calculated and experimentally determined strains, the flow of force and the crack pattern. To assess the quality of the post-test calculations, the test results were also verified with the two commercially available finite element programs SOFISTIK [14] and ABAQUS [15]. Furthermore, a selected plate test is used to discuss the influence of the idealisation of the reinforcement steel stress-strain relationship on the load-deformation behaviour of the plates. It is shown that the calculated deformation capacity of the slabs is strongly dependent on the chosen idealisation of the constitutive law.