Seismic behaviour of ashlar stone masonry walls with enhanced mortar joints

Stone masonry walls may be constructed using different types of stonework. This paper investigates the effectiveness of a technique that strengthens traditional ashlar stone masonry by embedding polymer mortar and steel bars in bed joints. The seismic behaviour of stone masonry walls with enhanced mortar joints is experimentally evaluated. Seven single-bay, single-storey wall specimens were fabricated and tested under different combinations of constant vertical loads and reversed cyclic lateral loads. One specimen was constructed using a traditional construction method; the other six specimens were constructed similarly, but their joints were strengthened with a combination of embedded polymer-based mortar and steel reinforcing bars. The influence of applied normal stress and strengthening method on the failure mode, lateral resistance, strength degradation, stiffness degradation, energy dissipation and ductility was investigated. The experimental results show that strengthening the joints effectively enhances the lateral load-carrying capacity and integrity of stone masonry walls. As expected, an increase in vertical load increased both the lateral strength and pre-peak stiffness of the tested specimens, but decreased the ductility. Within the limitation of the present tests, the failure mechanisms of the stone masonry walls were dominated by either diagonal stepped cracks or slip-shear cracks, depending on the specific strengthening method.