Seismic fragility assessment for post-1977 high-rise reinforced concrete structures in Romania

This study deals with the seismic fragility assessment of high-rise reinforced concrete (RC) structures in Romania designed after the major Vrancea intermediate-depth earthquake of March 4, 1977. Firstly, the evolution of Romanian seismic design codes employed before (P13-63 and P13-70) and after (P100-78/81) the Vrancea 1977 seismic event is presented. The influence of the above-mentioned seismic event on the seismic zonation of Romania is also discussed in the context of seismic design codes. Secondly, the damage information of pre-1977 high-rise RC structures during the March 4, 1977 Vrancea earthquake is presented and discussed. The seismic fragility assessment is performed by employing incremental dynamic analyses for both high-rise RC frames structures, as well as for high-rise RC shear walls structures which were widely used for residential purposes. For incremental dynamic analyses, ground motion datasets characteristic for the seismic conditions of Romania are selected and further employed. The results of the analyses show an increase of 30-40% of the median peak ground acceleration corresponding to various damage states for post-1977 RC frames and RC shear walls structures, as compared to the pre-1977 ones.