Seismic Performance of a Reinforced Concrete building not designed to withstand Earthquake Loading

The evaluation of the seismic behaviour of buildings not designed to resist earthquake loading represents a subject of great practical value and of high computation cost. For this reason in the last years many authors have developed simplified methodologies, based on pushover analyses that, with a reduced computational effort if compared with dynamic nonlinear analyses, are able to give a reliable measure of the resistance under earthquake loading. In the paper the seismic resistance of a RC building that has been built in a high seismic area without any seismic provision, is assessed by means of procedures based on pushover and dynamic nonlinear analyses performed on three-dimensional finite element models as well as simplified procedures based on equivalent singledegree- of-freedom systems. The results that have been obtained clearly show the high vulnerability of the structure for which a seismic retrofit is recommended. In a companion paper the seismic resistance of the building after a retrofitting which includes a partial reinforcement of the existing structure and base-isolation is investigated.