IDENTIFICATION AND PROPOSITION OF A LOCALLY UPDATED DAMPING MODEL FOR REINFORCED CONCRETE ELEMENTS

Earthquake events in recent years have led governments to focus on risk structures safety. Performative models integrating a fine representation of physical phenomena are required to ensure the viability of such structures. Notably, the reinforced concrete structure behaviour under seismic loading can be described through nonlinear dissipative phenomena. These phenomena can be defined : (i) at the local scale with a thermodynamic framework considering damage, friction, unilateral effect and plasticity nonlinear phenomena, and (ii) at the global scale, usually with viscous damping. In [1], a numerical benchmark was performed to compare different damping formulations used in the literature compared with experimental data. Energy analyses were also of interest, and it was demonstrated that the more dissipative phenomena are modelled at the local scale, the more the global response of the structure is accurately characterized. However, such damping formulations showed difficulties in accurately modelling the energy dissipations. So, in [2], a damping identification method has been proposed using a one-degree-of freedom (SDOF) system. That time-dependent method allowed identifying two locally updated damping models depending on the expected complexity. This paper aims to transpose the proposed locally updated models in the case of multi-degrees-of-freedom (MDOF) systems. An algorithm is proposed to compute the locally updated damping matrices in the case of a multifiber model. Then, dynamic computations are performed, and results are again compared with experimental data, but also with the tangent stiffness matrix proportional viscous damping. The global dynamic responses appear similar, but the energy dissipations seem more representative of physical phenomena, mainly when using the friction variable for the damping updates.