Strengthening of Historic Masonry Walls Using GFRP Grids Embedded into Inorganic Matrices

The paper presents a compilation of some of the author's research results related to the use of composite grids as shear strengthening materials historic masonry members. Glass Fiber Reinforced Polymer (GFRP) grids was used to strengthen unreinforced barely-cut stone masonry and clay brick walls. Unreinforced Masonry building (URM) panels were evaluated in-site under lateral loading. Various GFRP configurations were used to repair or retrofit undamaged masonry wall panels. The URM panels were loaded to ultimate condition under two test methods: in-plane diagonal compressive force (diagonal compression test) and in plane horizontal lateral force (shear-compression test). Tests were carried out in situ on panels cut from three different historic buildings in Italy: two in double-leaf rough hewn rubble stone masonry in Umbria and L’Aquila and another with solid brick masonry in Emilia. Test results indicate that application of GFRP grid embedded into an inorganic matrix (hydraulic based mortar) is an effective retrofit scheme for the wall panels, becausethe in-plane capacity of the strengthened walls increased significantly both for undamaged and repaired panels