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

Abstract

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.