Considerations regarding the retrofit intervention of Santa Maria di Collemaggio basilica in L'Aquila following 2009 Italian earthquake

The 2009 L'Aquila, Italy, earthquake highlighted the fact that seismic vulnerability of historic masonry buildings palaces has increased because of "strengthening" retrofit work that has been done in the last 50 years. Italian seismic standard recommended use of traditional reinforcement techniques such as replacing the original wooden roof structure with new reinforced concrete or steel elements, inserting reinforced concrete tie-beams in the masonry and new reinforced concrete floors, and using reinforced concrete jacketing on the shear walls. L'Aquila earthquake has shown numerous limitations of these interventions, because they lead to increased seismic forces (due to greater weight) and to deformations incompatible with the masonry walls. This paper provides a discussion of technical issues pertaining the seismic retrofit of Santa Maria di Collemaggio basilica and in particular the limitations of the last (2000) retrofit intervention. Considerable damage was caused at the church because of questionable actions and incorrect and improper technical choices.