Abstract
The structural response of unreinforced masonry buildings designed for gravity load only or with reference to obsolete seismic provisions is widely studied in the literature in order to define proper strengthening strategies and solution to mitigate the seismic risk. However, the critical analysis of the effectiveness of past used strengthening solution is still lacking. To fill such gap, the present study deals with the evaluation of the seismic performances of buildings in Campi Alto struck by the 2016 central Italy seismic sequence. The behaviour of buildings in Campi Alto is compared with that of buildings in Norcia. A large part of the buildings in these two towns was strengthened between 1980 and 2000 during the reconstruction processes following previous earthquakes which occurred in 1979 and 1997. However, the strengthened buildings in Norcia reported limited damage while a significant and widespread level of damage was detected on several strengthened buildings in the hamlet of Campi Alto. This study focuses on the buildings in Campi Alto with the aim of investigating on the reasons of their unsatisfactory behaviour. Thus, the seismic action experienced by buildings in Norcia and Campi Alto is initially compared and the main vulnerabilities of these buildings are also evaluated. Then, 20 projects of strengthening interventions submitted to the Civil Engineering Department of the Umbria Region between 1984 and 2012 have been herein analysed and discussed in order to focus on the effectiveness of the strengthening solution adopted in the past. The analyses of such projects and of the empirical damage detected after the 2016 seismic sequence is a unique opportunity to derive useful information for future applications.
Highlights
The damage analysis after significant earthquakes allows the identification of the vulnerability of different types of existing structures; a seismic event represents an occasion to better understand the response of existing buildings and, to plan and carry out experimental and analytical studies aimed at defining new strengthening strategies and solutions or construction details to reduce the structural deficiencies.Several studies available in literature focused on the structural response of unreinforced masonry buildings (Sayin et al 2013, Ortega et al 2017, Gautam et al 2016) in case of seismic events
20 projects of strengthening interventions submitted to the Civil Engineering Department of the Umbria Region between 1984 and 2012 have been analysed and discussed in order to focus on the effectiveness of the strengthening solution adopted in the past
The present study focuses on the behaviour of strengthened masonry buildings located in Campi Alto and Norcia
Summary
The damage analysis after significant earthquakes allows the identification of the vulnerability of different types of existing structures; a seismic event represents an occasion to better understand the response of existing buildings and, to plan and carry out experimental and analytical studies aimed at defining new strengthening strategies and solutions or construction details to reduce the structural deficiencies. It has rarely been possible to evaluate the real seismic response of a significant number of strengthened masonry structures to date: a recent study on the effectiveness of strengthening solution adopted in the reconstruction process of past earthquakes has been carried out by the authors (Sisti et al 2018; Borri et al 2018). It focuses on the structural response of masonry buildings in the historic centre of Norcia after the central Italy 2016 seismic sequence. This to fully correlate the damage detected after the seismic sequence to the buildings’ characteristics and details of strengthening solutions that may have strongly influenced the seismic response of such buildings
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