NUMERICAL SIMULATION OF CONCRETE STRUCTURE PILE CAP (“D REGION”) USING CONCRETE DAMAGED PLASTICITY AND NON-LINEAR ANALYSIS

Resumo

The design of reinforced concrete structures aims to define the amount and distribution of
steel rebars (reinforcement) required in the elements. In complex situations, the Strut and Tie Method is
used for design parts that are subject to complex stress distributions (known in the literature as "D
Regions"). One of the difficulties in the application of the method is the determination of the most
probable distribution of tensions that the part will suffer, since it depends on its own geometry and the
amount of reinforcement used. For this reason, on an initial step, elastic analyzes can be used to suggest
a probable field of stresses to be used in the definition of the Strut and Tie Model. However, in the
ultimate strength, the stress distribution can be affected by non-linear effects like non regular
constitutive relations of the materials (concrete and steel), by damage processes that the part will suffer
and also by the distribution of reinforcements. The objective of this work is to present nonlinear
computational analysis of several elements of reinforced concrete, considering the distribution of
reinforcement, in order to evaluate its real behavior in the ultimate state, and to compare with the results
predicted by the usual methods of design, mainly the Strut and Tie method. In order reach this objective,
the models of reinforced concrete are developed through the software of finite elements ABAQUS,
considering Concrete Damage Plasticity. The models constructed on this paper consider the
reinforcement distribution, including the constructive ones, trying to evaluate its influence in the field
of tensions and its resistant capacity. Several situations are examined and the results are compared with
the conventional design methods or with the Strut and Tie Model. The developed examples confirm that
the stress field and the resistance capacity are affected by the reinforcement distribution. In this way,
the present work intends to discuss how the Strut and Tie models are affected by non-linear behavior
and by the designed reinforcements.