In-plane behaviour of wall panels reinforced using rigid GFRP grids

Extensive research has shown that Fabric Reinforced Cementitious Matrices (FRCM) are effective for strengthening masonry buildings. However, different types of FRCMs are actually available on the construction market and a reliable design procedure does not exist. Externally bonded composite rigid grids, embedded into thick (30-100 mm) coatings, were used in this study as a means of reinforcing historic wall panels subjected to in-plane loading. The paper summarizes the results of several experimental studies carried out in the laboratory and on-site in the Italian district of Perugia and a design procedure of the reinforcement intervention is also proposed. The aim is to identify a retrofitting method for historic masonry wall panels which will improve inplane seismic performance, without significantly altering the mechanical behaviour of the building. The desired retrofitting method must also meet the requirements imposed by the conservation bodies in terms of reversibility of the reinforcement and compatibility with the original masonry structure. Different types of rigid grids were tested: the parameters considered were the grid’s type and spacing and the masonry typology. The investigation was conducted on full-scale wall panels. The results indicate that the masonry shear capacity is affected by the reinforcement application and several mechanical parameters also increased significantly. As a consequence of the results, a modified version of a pre-existing analytical model, provided by researchers in the field, is also proposed and discussed for use in designing FRCM strengthening schemes against in-plane seismic actions.