Out-of-plane behavior of clay brick masonry walls retrofitted with flexible deep mounted CFRP strips

The installation of carbon fiber reinforced polymer (CFRP) strips to deep vertical slots in masonry using a flexible adhesive was developed as a minimally-invasive and cost-effective out-of-plane seismic retrofitting technique for clay brick unreinforced masonry (URM) buildings. The purpose of the current experimental campaign was primarily to investigate the out-of-plane performance of full-scale, flexible deep mounted (FDM) CFRP retrofitted masonry walls. An additional objective was to assess the validity of existing model for determining the out-of-plane capacity of FDM CFRP retrofitted walls. In the experimental testing program, nine full-scale masonry walls were tested, of which six walls were retrofitted using the FDM CFRP technique. A new six point-bending test setup was adopted for quasi-dynamic cyclic testing with loading rates up to 30 mm/s. Experimental results confirmed the significant increase for out-of-plane lateral resistance and displacement capacity for the FDM CFRP retrofitted specimens with respect to the URM specimens. By implementing multiple bed joint-crack formation and cyclic degradation of the masonry, the proposed engineering model provided a good approximation of the experimentally obtained moment – mid-span displacement relations.