In-plane behavior of tuff masonry panels strengthened with FRP diagonal layout

The present paper deals with a quantitative analysis of the shear strength behavior of masonry panels strengthened with diagonal layout. The objective of the study is to progress towards understanding the shear strength contributions from masonry and FRP to the lateral resistance of strengthened panels. To this aim, the experimental data set from 7 masonry panels subjected to shear-compression loading obtained by [Marcari 2007] have been used. Additional information includes the local behavior of the shear reinforcement and its effects on the global response of the panels. In particular, FRP strain profiles along the plies (i.e. the transferrable tension force within FRP), the lateral drifts and lateral load achieved by the panels at the occurrence of the debonding of the plies or at the peak strains are discussed. The role of the anchorage systems used for the diagonal plies (namely full wrapping and partial-wrapping) on the macro-response of the panels is also examined. The experimental results show the effectiveness of the anchorage system in restraining the FRP at the anchored edges, avoiding premature failure due to FRP debonding. As a result, the specimens were allowed to develop their full lateral resistance. Quantitative evaluation of the contributions from masonry and FRP is performed by using a truss model approach, combined with a suitable diagonal shear strength criterion for masonry. Accuracy of the procedure is assessed through comparison with the experimental data.