Titanium ties for the reinforcement and repair of masonry constructions: Experimental and numerical investigation

Titanium offers very high durability and specific strength, low thermal expansion, and its cost has dropped significantly in recent decades. In earthquake engineering and masonry conservation, where material durability and reversibility are essential, titanium combined with inorganic matrices aligns well with these requirements and has attracted growing research interest. Out-of-plane collapse of buildings facades is common during earthquakes, especially when connections between wall panels are weak. This study investigates the use of titanium threaded rods to strengthen these connections. Two reduced-scale brickwork specimens were constructed in the laboratory and reinforced with titanium rods embedded in the horizontal mortar joints to enhance out-of-plane resistance by anchoring them to the return walls. Their behaviour under out-of-plane loading was assessed by examining failure modes, deformation, and load capacity. A complementary finite element model using detailed micro-modelling was developed to capture masonry heterogeneity and the localized damage observed experimentally. By modelling each material component, the analysis realistically simulated cracking, sliding, and interface separation, enabling direct comparison with test data. Overall, the combined results show that titanium threaded rods markedly improve wall connections and significantly enhance the out-of-plane bending strength of masonry constructions.