On the monitoring of historic Anime Sante church damaged by earthquake in L’Aquila Salvatore Russo * ,† Structural Engineering, Head Research Unit of ‘Assessment of Monuments’, IUAV University of Venice, Dorsoduro 2206, 30123 Venice, Italy ABSTRACT The paper shows the activity of a 2-year static and dynamic monitoring activity to check the structural response and the actual level of damage of a historic church hit by earthquake in L’Aquila (Italy) in 2009. Structural health monitoring was carried out with accelerometers and transducers that recorded time histories of the main earthquake-induced ground motions and ambient vibrations. The paper focuses particularly on residual performance and assessment of the ancient church after six earthquake response data set—because of the seismic swarm—via a modal identification of output-only systems by using frequency domain decomposition. In this way, fundamental frequency, mode shapes, damping ratios and displacements can be estimated without knowing the input that has excited the system. The dynamic monitoring provides also a way to check possible drops of tension in the cables and relaxation in the FRP belts used for safety. Efficiency and reliability of modal identification of basilica-type churches, via the dynamic response of macro-elements only in comparison with the whole analysis, are finally proposed. Copyright © 2012 John Wiley & Sons, Ltd. Received 20 February 2011; Revised 16 August 2012; Accepted 27 September 2012 KEY WORDS: damaged monument; dynamic identification; health monitoring; modal analysis; macro-elements 1. INTRODUCTION The need for non-obtrusive investigation and monitoring monument preservation state—both for general and seismic assessments—is perceived nowadays as of primary importance; this is particularly true in Italy, whose architectural-historic heritage is one of the richest and most valued in the world [1–4]. Structural identification with non-destructive procedures and tools has been achievable since a long time, with the aid of experimental dynamic analysis performed with operation [5] or experimental modal analysis [6–13] techniques. This paper shows the case of the well-known Anime Sante ancient church in L’Aquila hit by earthquake in 2009 in which ambient and seismic vibrations have been used to check damaged historic masonry structure. In the last years, the identification of the basic dynamic engineering parameters—i.e. natural frequen- cies, mode shapes and damping coefficient—by analysing environment-induced vibrations has been deeply explored [14–20]. In particular, the definition of experimental natural frequencies and mode shape from the dynamic response alone is important for buildings of historical interest, to define maintenance and restoration strategies without invasive testing. This kind of study has been already proposed by other authors [21–25] and also for monumental building such as the Colosseum [26]. With modal updating techniques, on the grounds of published research [27], damage can be evaluated [28–30], and maintenance or structural rehabilitation can be planned paying due attention to the response to ambient-induced *Correspondence to: Salvatore Russo, Structural Engineering, Head Research Unit of ‘Assessment of Monuments’, IUAV University of Venice, Dorsoduro 2206, 30123 Venice, Italy. † E-mail: russo@iuav.it STRUCTURAL CONTROL AND HEALTH MONITORING Struct. Control Health Monit. 2013; 20:1226–1239 Published online 28 October 2012 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/stc.1531 Copyright © 2012 John Wiley & Sons, Ltd.