Cyclic Non-linear Analysis of Complex Reinforced Concrete Structures with GLRC_HEGIS Model

The following master’s thesis was written during a period of foreign mobility, with a duration of 5 months, which was spent at Egis, a French group leader in the engineering sector. In particular, the internship was carried out in the Egis Industries (nuclear department of EGIS group), within the EAS (Egis Advanced Solutions) team. The internship aimed at validating GLRC_HEGIS nonlinear constitutive model developed by Miquel Huguet Aguilera for the software Code_Aster, by means of a several simulations aimed at reproducing the behaviour of real case studies. This constitutive law is able to reproduce the main nonlinear phenomena that characterise the behaviour of RC (reinforced concrete) elements: concrete damage, concrete cracking, bond-slip stress and yielding of steel reinforcement bars. The validation of the model has been carried out through three main analyses: (i) comparison with experimental results of reinforced concrete walls subjected to horizontal cyclic loads in plane shear, (ii) the comparison with other non-linear global models available in Code_Aster and (iii) comparison with experimental results of reinforced concrete elements subjected to pure out-of-plane bending. The first considered experimental test includes the four walls designed and tested in the framework of the French national research project CEOS.fr (Behaviour and Assessment of Special Structures. Cracking - Shrinkage). Shear-wall specimens were designed in order to simulate the behaviour of the nuclear power plant walls submitted to the seismic action. The four walls are subjected to horizontal cyclic loading in plane shear (reversing for three walls and non-reversing for one) and differ from each other or by the strength class of the concrete used, or by the amount of reinforcement or by the type of load applied. The numerical results obtained were compared with the available experimental ones, in terms of force-displacement curves and crack opening on the walls surface. Then, the GLRC_HEGIS global model was compared to other global models for RC plates available in Code_Aster (GLRC_DM, DHRC and EIB) already implemented in Code_Aster and has been analysed the case of cyclic pure flexion test. In particular, the behaviour of a reinforced concrete plate subjected to constant cyclic bending moment was studied, implementing the results already obtained with two different load cases. At first, the number of cycles was increased from one to six and subsequently an increasing moment was applied. The comparison with the other models mainly concerned the energy dissipated during the load cycles and the applied rotation-moment curves. To extend the results obtained so far, the model was used to simulate an experimental test of a three-point RC beam subjected to pure bending. The numerical results have been compared with the experimental ones and important conclusions have been reached. In particular, by studying both behaviours (membrane and flexural) it is noted that the general behaviour of the model is governed mainly by the concrete damage. In fact, for all the models the same non-linear parameters were used except those relating to the damage to the concrete. That means that concrete damage is the only phenomena that behaves differently in membrane and in bending solicitations. This aspect makes it possible to standardize the model and further eliminate the small uncertainty that governs the choice of parameters that must be used.