NUMERICAL MODELING OF REINFORCED CONCRETE BEAMS USING THE COMPOSITION OF TWO PLASTIFICATION SURFACES

Resumo

In order to consider the multiaxial behavior of concrete, several plastification and rupture
surfaces have already been proposed, such as the Ottosen surface or the Willam-Warnke surface.
However, the use of these surfaces in numerical finite element models can often lead to convergence
difficulties, due to the complexity of their formulations. In this context, the present work simulated
numerically the behavior of two reinforced concrete beams tested experimentally in a previous work,
using ANSYS software, version 19.2, with a new elastoplastic model available in the recent versions of
this software, denominated DP-Concrete. This model uses the composition of two simpler plastification
surfaces, one for tensile behavior, which can be a Rankine or a Drucker-Prager surface, and another
Drucker-Prager surface for compressive behavior. This surface composition allows simulating the large
differences in the concrete behavior under tension and compression, which would not be possible with
a single Drucker-Prager surface. In addition, because it is a newly available material model, it can be
applied to the SOLID186 element, which is classified as a current-technology element by this software,
and therefore is compatible with several current ANSYS features, such as the generation of embedded
elements by the mesh-independent method, through the MESH200 guide elements, which were also
used in this work. In order to consider the cracking and crushing phenomena, different softening and
hardening laws available in the software were used. The obtained results were compared with each other
and with the results of the experimental tests. In addition, numerical analyses were performed with a
customized material model based on the Ottosen criterion, whose results were also used for comparison
purposes. It was concluded that the DP-Concrete model is an adequate modeling strategy for the concrete
behavior, and its main advantages are its simplicity, flexibility and compatibility with other current
ANSYS functionalities.