Compressive behavior of brick masonry columns confined with composites embedded in the horizontal mortar joint

Abstract

The application of composite materials embedded in the horizontal mortar joints to strengthen masonry structures with insufficient load-bearing capacity has shown beneficial effects in terms of improving mechanical behavior and preserving the aesthetics of the building. To investigate the effectiveness of this strengthening technique, concentric axial compressive tests were performed on eight masonry columns, including two unconfined columns, five specimens confined by carbon fiber reinforced polymer (CFRP) plates, and one specimen confined by engineered cementitious composite (ECC). The failure mode, strength, deformability, and energy dissipation capacity of the specimens were investigated. The effective tensile strain of the CFRP plates was also discussed. The results showed that the CFRP-confined masonry columns exhibited brittle failure, which was characterized by the debonding failure of the CFRP caused by the sudden fracture of the epoxy resin, while the failure of the ECC-confined masonry column exhibited significant ductility, the reason for which was that the propagation of vertical cracks was delayed due to the strain-hardening characteristics of the ECC. The reinforcement technique was effective for masonry columns in obtaining better compressive performance. The peak strength and energy dissipation of the confined columns were increased by a maximum of 86.31% and 115.71%, respectively. A non-uniform distribution of the effective tensile strain of the CFRP plates along the perimeter was observed. In addition, a simple strength model for masonry columns confined by embedded material in the horizontal mortar joints was developed based on the best-fit analysis of a database assembled from the existing literature and the current study. The predictive capabilities of the proposed model and an existing model for the compressive strength of confined masonry columns were analyzed.