Seismic analysis of a urban block in Faial Island of Azores

Abstract

The paper deals with numerical seismic analysis of an urban building block located in Faial island,Azores, hit by an earthquake on July, 9th 1998. It includes two different construction types, mostlytraditional masonry structures and a reinforced concrete structure building in one block side. Theanalysis was supported by laboratory and in-situ tests, namely ambient vibration measurements onthree traditional houses and on the RC building. Experimental mode shapes and vibrationfrequencies allowed mechanical parameter calibration for numerical models. Finite element timedomain dynamic analyses were made using the accelerograms recorded during the earthquake.This paper describes the seismic analysis of the global block as is and also parametric studies toassess the effect of possible reinforcing solutions in floors/walls and of the RC building. The mostvulnerable block zones were identified as well as their interaction with the remaining structures.When possible reinforcing schemes were considered, results allowed assessing their efficiency onimproving the block behaviour. Interdependency between different block elements was evidenced,showing that reinforcing may be done by means of single interventions in localized zones.However, stress redistributions caused by interventions must be taken into account becausestiffness variations may increase stresses in reinforced zones, which means that individualbuilding might not be appropriate.