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Effectiveness of seismic strengthening to repeated earthquakes in historic urban contexts: Norcia 2016

Valentina Putrino (Department of Civil Environmental and Geomatic Engineering, University College London, London, UK)
Dina D’Ayala (Department of Civil Environmental and Geomatic Engineering, University College London, London, UK)

Disaster Prevention and Management

ISSN: 0965-3562

Article publication date: 3 May 2019

Issue publication date: 6 January 2020




The purpose of this paper is to discuss the dynamics of the evolution of damage to the residential buildings within the city walls of Norcia during the six-month seismic swarm that hit Central Italy in the period 24th August 2016 to end of January 2019. This is accomplished by comparing the damage recorded by the Italian Civil Protection usability form (AEDES form) during this period after each event.


First, these outputs are compared with a qualitative assessment conducted by means of omnidirectional camera (ODC) imagery collected on site by the authors, to explore the ability of this technology to support post-earthquake damage assessment. The damage level attributed with these two techniques is then further compared with the output of the analytical vulnerability assessment method FaMIVE, which allows to correlate damage to vulnerability. Specifically, the objective is to investigate the efficacy and performance of historic and recent strengthening interventions.


Results show that there is a good correspondence between AeDES and ODC assessments for low to medium damage grades (DG). Discrepancies in higher DGs are discussed in light of the different levels of information that can be recorded by using the two tools. The efficacy of strengthening is also well captured by the FaMIVE method. The procedure estimates a decrease of almost 40, 25 and 20 per cent of the total number of buildings failing out-of-plane, respectively, for the three seismic events considered, when restraining elements are in action.

Research limitations/implications

The analysis conducted in this work make use of deterministic values of Norcia’s masonry fabric characteristics that have been found in literature, thus implying that neither the probabilistic aspects nor the related uncertainties have been properly investigated and addressed. However, this limitation is to be considered within the more general context of the legislation for the preservation of historic buildings which limits substantially any type of semi-destructive tests, hence limiting the reliability of the values available in literature. This in turn affects the decisions informing the design and implementation of strengthening interventions which can be confidently considered reliable and effective.


The paper addresses for the first time a systematic investigation of damage progression in historic masonry structures, part of urban aggregates in heritage cities. The current urban fabric is discussed in view of historic building codes as the basis for determining the present seismic vulnerability of the historic city centre of Norcia. The study provides new data sets for the city of Norcia and develops a statistical correlation between cumulative damage and analytical vulnerability functions for heritage buildings exposed to a swarm of earthquakes. The analytical assessment of the effect of historic strengthening is totally novel.



This research was funded by the 2017 EEFIT Research Grant. The research topic was initiated after the 2016 Central Italy EEFIT mission, of which Professor Dina D’Ayala (the co-author) was the Team Leader. Fundamental to the considerations included in this work are the data provided by the Umbria Region Civil Protection Responsible Officer Nicola Berni and the Technical Scientific Officer Paolo Putrino. Help and support during the site investigation was provided by Miss Chen Huang, PhD Candidate at the University College London, Civil Environmental and Geomatic Engineering Department. Great support during the preparation of the proposal was given by Paolo Perugini, Senior Engineer at Arup and Dr Matthew Free, Director at Arup. Logistic support was provided on site by local academic partners from the University of Perugia and the University of Ferrara. The authors wish to thank Professor Antonio Borri, Professor Andrea Giannantoni, Dr Giulio Castori and Dr Alessandro De Maria for their valuable help prior, during and after the field mission.


Putrino, V. and D’Ayala, D. (2020), "Effectiveness of seismic strengthening to repeated earthquakes in historic urban contexts: Norcia 2016", Disaster Prevention and Management, Vol. 29 No. 1, pp. 47-64.



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