Seismic performance of irregular existing RC framed structures

This paper deals with the seismic performances of irregular existing reinforced concrete framed structures. More specifically, the effect of the non coincidence between the mass and the stiffness centers on the seismic response of these structures is investigated. The study is performed on a sample 4 storey three-dimensional framed structure designed for vertical loads only, according to the provisions reported in the Italian codes of the 60s. The seismic response of the structure is evaluated performing a nonlinear incremental dynamic analysis with the computer code SeismoStruct. The results, compared with the limit values provided by FEMA 356 for the different limit states, evidence that the considered irregularities significantly affect the seismic performance of the structure even for low values of the PGA.