Floor spectra for bare and infilled reinforced concrete frames designed according to Eurocodes

In this study, nonlinear time-history analyses are performed to assess the floor response spectra of bare and infilled reinforced concrete framed buildings with different number of stories and designed according to Eurocode provisions for different intensity levels of the seismic action. Infill walls are modeled by neglecting and by accounting for the effects of their out-of-plane response and of the in-plane/out-of-plane interaction. To this aim, a recent out-of-plane response model is updated and improved. The results of the numerical analyses are compared in order to assess, first, the different floor spectra obtained for bare and infilled buildings and, second, the effect of the in-plane/out-of-plane interaction on the results obtained for infilled buildings. The main parameters influencing the shape and the amplitude of floor response spectra are investigated, namely higher vibration modes, structural nonlinearity, and damping of the secondary element. This is also performed with the support of the discussion and application of current code and literature formulations. Based on the results of the numerical analyses, a simplified code-oriented formulation for the assessment of floor response spectra in bare and infilled reinforced concrete framed structures is proposed. The proposed formulation may be a useful tool for the seismic assessment and safety check of acceleration-sensitive nonstructural components.