Bed joint reinforcement of shear walls using threaded titanium rods

Shear walls in historic constructions often require retrofit. The lateral load capacity is frequently insufficient to withstand seismic actions. Threaded titanium rods embedded in mortar bed joints have emerged as a viable solution to reinforce brickwork shear walls. The use of a high tensile strength and ductile material (titanium alloys), with a high degree of reversibility of the retrofit intervention, is promising as it represents a new opportunity in masonry conservation. Aiming at studying the effectiveness of the titanium rod repair, this research had a twofold goal: 1. laboratory tests were performed to investigate the structural response of reinforced walls at macro-scale level; 2. a numerical modelling strategy was implemented to fill the knowledge gap regarding the material properties of brickwork masonry (English and Flemish bond). Quasi-static cycling loading tests performed on full scale (1200x1200 mm, two wythes thickness) specimens demonstrated how bed joint reinforcement using threaded titanium rods produced a significant increase in the lateral load and deformation capacities. To provide an effective tool for predicting all material parameters, as input data, and for designing the proposed strengthening system, a step-by-step procedure - based on the use of digital image processing (DIP) techniques, homogenization theories and micro-modelling strategies - was therefore proposed.