VULNERABILITY OF TORSIONALLY SENSITIVE HISTORICAL BUILDINGS UNDER SEISMIC LOADS

The paper explores the effects of asymmetry in plan owing to the occurrence of slender wings in massive monumental and historical URM buildings that belong to the postrenaissance neoclassical school of architecture.Although it is common in buildings with flexible diaphragms to disregard the implications of torsion, in this particular case these effects are significant causing important differential displacements and therefore a high risk of damage in the wings.To study the problem, three-dimensional finite element models of a neoclassical building with asymmetric plan shape located in Thessaloniki, Greece, are analyzed to a strong ground motion that has been recorded in the region and their maximum seismic response is explored.This response is then compared with results obtained from application of the rapid seismic assessment procedure of unreinforced masonry buildings, which has been recently introduced by the authors and conclusions on the procedure's accuracy are derived.Emphasis is placed on the sensitivity of the torsional aspects of the response to the stiffness of horizontal diaphragms that is provided by the architectural forms of the era under investigation.Application of this rapid methodology enables easy inspection over the building's geometry to identify those characteristics that may predispose the tendency for a strong torsional component of response, but it may also help identify the efficacy of retrofitting through the addition of diaphragms as a strengthening approach that may mitigate the occurrence of damage.