Seismic response of masonry buildings in historical centres struck by the 2016 Central Italy earthquake. Calibration of a vulnerability model for strengthened conditions

Brought to light by the 1997 Umbria-Marche (Italy) earthquake for the first time, the theme of damage patterns of masonry buildings with structural interventions became urgent again in the 2016-17 Central Italy seismic swarm. On a sample of 2306 buildings within the seismic field, the 85% bears the signs of structural interventions. With the aim of inferring the vulnerability factors from damage of strengthened buildings, a close-up analysis revealed that interventions can cause damage to the structures on which they are applied because of i) poor detailing and ii) incompatibility among parts, old and new. These con-ditions limited the attainment of a building's box-like behaviour and, therefore, an unfavourable contri-bution of interventions was identified. Conversely, a favourable contribution was determined. The analytic comparison between the behaviour of building types with interventions and that of the vulner-ability classes of the European Macroseismic Scale (EMS-98) obtained a vulnerability model for empirical data. Buildings whose interventions had an unfavourable contribution are comparable with 'original', unreinforced ones; conversely, a favourable contribution permitted them to approach the behaviour of modern masonry structures. This work represents a first step towards the inclusion of strengthened buildings in the EMS-98 vulnerability system. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study analyzed masonry buildings with structural interventions and identified factors that could lead to structural damage, establishing a vulnerability model based on empirical data.