Seismic upgrading of historical masonry buildings with steel reinforced grout (SRG)

Seismic retrofitting of structures belonging to the architectural heritage requires meeting of constraints which are related to preservation of artistic features. Any developed intervention must do not change appearance, structural mechanism and must be also not invasive. These innovative principles, that are quite obvious from a cultural and artistic point of view, are very restrictive constraints to engineer’s jobs but innovative materials, such as composites, may be helpful in the matter. Such a philosophy was applied to the design process of the retrofitting intervention for on an ancient tower in the city of Trevi (Italy). This led to the opportunity of investigating the efficiency of an innovative composite materials, based on fine steel cords embedded in a cementitious matrix (Steel Reinforced Grout), representing the first case study where this material has been applied in the field. To increase the stiffness and the flexural strength of the walls, a reticular system, made of horizontal and vertical prestressed SRG laminates, have been applied on the external walls of the tower. The proposed strengthening method proved the effectiveness of SRG composite materials, able to allow the same advantages (low weight, easiness of execution, durability, etc.) proper of Fiber Reinforced Polymers (FRP), reducing installation and material costs, and inducing an increase of ductility. Preliminary analytical work shows that the same approach used for externally bonded FRP can be satisfactorily used for SRG.