How are the equivalent damping ratios modified by Nonlinear engineering demand parameters?

International audienceWhen attempting to predict the seismic response of reinforced concrete (RC) structures,a trade-off has to be found out between a precise and realistic representation of the dissipationsthrough material behavior law and a more efficient modeling exhibiting a controlledcomputational demand such as a Rayleigh-type damping model. Anyway, constitutive laws onlydescribe internal dissipation and models actually need a complementary dissipation term oftenchosen as a Rayleigh damping matrix to take into account external dissipation sources such asinteractions with the environment (for example air, fluids or non-structural equipment). Decouplingthese two contributions in global dissipation measurement from experimental tests is stillchallenging. To assess this problem, a numerical experiment is here presented. To this end,an experimental campaign has been carried out on RC beams set up on the AZALEE shakingtable of the TAMARIS experimental facility operated by the French Alternative Energies andAtomic Energy Commission (CEA). In this paper, the experimental campaign is first presented.Secondly, a suited constitutive model is formulated and identified from the experimental results.Third, numerical dynamic experiments are carried out in order to assess the influence of severalparameters on the energy dissipation and on the equivalent viscous damping ratio through twodifferent methods. The validity of these results is assessed on a numerical case where a nonlinearmodel and an equivalent linear model are compared with each other. Experimental resultsof dynamic tests are also used as reference in order to estimate the additional viscous dampingnecessary to take into account the whole energy dissipation