Composite Materials Research Volume 7 Issue 1 | 2018 | 1 Post-seismic Effectiveness of the Strengthening Work Carried Out with GFRP Applied to Historical Masonry Buildings: The Case Study of the Spoleto Cathedral Alessandro Grazzini 1 (*) , Stefano Agnetti 2 1 Assistant Professor, Department of Structural Geotechnical and Building Engineering, Politecnico di Torino. (*) corresponding author: ales- sandro.grazzini@polito.it 2 Civil Engineer Ph.D., Head of Technical Department, Kimia S.p.A., stefano.agnetti@kimia.it Abstract: The sequence of major earthquakes that has affected Italy in recent decades has required the use of new mate- rials and innovative techniques for the security of damaged buildings. Fiber Reinforced Polymer (FRP) represents a novelty in the field of seismic improvement techniques applicable also to historical masonry structures. The use of composite materials can respect the conservation principles of the monumental buildings. This study describes the ef- fectiveness of the seismic improvement techniques carried out by means of FRP in the Spoleto Cathedral (Italy) after the 1997 Umbria-Marche earthquake. The strengthening work concerned the making safe of damaged vault struc- tures by means of gluing fiberglass bands (GFRP). After 20 years, during the 2016 Amatrice-Norcia earthquake, near Spoleto, the cathedral reinforced with the GFRP bands has not suffered any damage demonstrating the effectiveness of the seismic strengthening techniques. Keywords: Historical buildings; Seismic improvement; GFRP; Strengthening work, Fiberglass band. 1. Introduction The seismic vulnerability of the existing building heritage represents a complex problem within a highly seismic area. Recently the Centre area of Italy was hit by a big seismic sequence that in 2016 destroyed the village of Amatrice (6.0 magnitude) and caused much damage to Norcia (6.5 magnitude). Many historical buildings col- lapsed or were seriously damaged [1] . The Central Italy had been hit by other seismic events of similar intensity and destruction already 40 years ago (1979 Valnerina earthquake, 5.8 magnitude) and 20 years ago (1997 Um- bria-Marche earthquake, 6.0 magnitude). Therefore it is very interesting to verify how the strengthening tech- niques, applied after the previous earthquakes, have re- sponded to the stresses of the last earthquake (2016 Amatrice-Norcia). It is also an opportunity to analyse how these strengthening techniques have evolved over time, with the introduction of lighter and more resistant modern materials, adaptable to any context, even the monumental artistic one. Many types of damage and vulnerability can also be recovered with innovative and lighter materials, such as FRP bands. The choice of strengthening materials must be very careful so that ma- terials with physical-mechanical characteristics compati- ble with the historical masonry support are applied [2] . After the 1997 Umbria-Marche earthquake, a de- tailed experimentation of the FRP application also began on historical masonry structures, considering the need to strength a large number of damaged buildings [3] . Copyright © 2018 Alessandro Grazzini et al. doi: 10.18282/cmr.v7i1.524 This is an open-access article distributed under the terms of the Creative Commons Attribution Unported License (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.