Seismic performance of a reinforced concrete building not designed to withstand earthquake loading

Abstract

This paper describes how the evaluation of the seismic behavior of buildings not designed to resist earthquake loading represents a subject of great practical value and of high computation cost. For this reason in past few years many authors have developed simplified methodologies, based on pushover analyses that, with a reduced computation effort if compared with dynamic nonlinear analyses, are able to give a reliable measure of the resistance under earthquake loading. In this paper the seismic resistance of an RC building that has been built in a high seismic area without any seismic provision, is assessed by the means of procedures based on pushover and dynamic nonlinear analysis that was performed on three-dimensional finite element models as well as simplified procedures that were based on equivalent single-degree-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 retrofitting, which includes a partial reinforcement of the existing structure and base-isolation is investigated.