Effect of the seismic input on nonlinear response of r/c building structures

The effects of the variability of seismic input on system structural response are investigated. Non linear time history analyses are performed using as input sets of accelerograms satisfying the compatibility criteria with an elastic design spectrum according to the Eurocode 8. The response of elastic SDOF systems, in terms of spectral acceleration, is analyzed; the same parameter, for corresponding non linear SDOF systems as well as ductility demand and strength reduction factors, is also discussed. The analyses are extended to a r/c multi-storey space frame, which is designed according to Eurocode provisions. The main conclusion of the paper is that, when the input is selected according to the Eurocode 8 provisions as recorded accelerograms, a "natural" mean CoV of spectra ordinates is expected; it proportionally conditions the CoV of the parameters characterising the non linear response of structures.