The effects of the seismic input on the seismic response of RC buildings

This work is aimed at investigating the variation of the seismic response of RC structures subjected to different ensembles of ground motions in the nonlinear dynamic analy-sis for the seismic assessment of existing RC buildings. At the current time indeed, all the main International Seismic Codes provide a soil classification which is based on the shear wave velocity, the soil morphology and the assumed distance from the fault source. Depend-ing on the soil properties, a suitable elastic spectrum is provided, defined on the basis of av-erage properties assumed for the soil. To perform a nonlinear dynamic analysis, an ensemble of ground motions compatible to the elastic spectrum must be selected. The ensemble can be made by ground motions compatible to the Code spectrum for the assumed soil-type, or, al-ternatively, by assuming the ground motions to be consistent with the bed rock Code spectrum and by filtering them according with the specific stratigraphy of the site soil. In this work a comparison among these different approaches, all compatible to the European (Eurocode 8, EC8) and Italian (NTC 2008) Code provisions, has been made on a case-study, i.e. a real ir-regular RC Italian building. The comparison has been made in terms of seismic response, i.e. by checking the maximum displacement and interstory drift induced by the assumed ensem-bles of ground motions.