A retrofitting technique using steel grids for existing masonry panels: a numerical and analytical study

The current research focuses on a numerical and analytical study aimed at investigating the efficiency of a steel-based reinforcement system suitable for existing masonry walls. The application of such a retrofitting technique, which consists of glued thin steel grids applied on both faces of a masonry panel, is reversible, cheap and easy to be executed and appears to be suitable especially for buildings with concrete slab or inter-stories beams to which the steel elements could be anchored. The study is based on a reference experimental test carried out at the Politehnica University of Timisoara (Romania), within the European FP6 project PROHITECH. The reference test provided the application of a constant vertical compression and cyclic horizontal displacements to an unreinforced brick-cement mortar wall in full-scale (1500 x 1500 x 250 mm), to which was conferred a double-fixed constraint condition. Based on the experimental evidences, a reference numerical model has been implemented in ABAQUS, by adopting a plastic-damage material and a macro-element approach for the masonry modelling. Hence, in order to determine a design criterion of the studied system, a comparison with the analytical formulations available in the current Italian and European codes for the unreinforced configuration is presented in this study. Then, a wide parametric study on the investigated retrofitting technique has been carried out by varying thickness and spacing of steel grid elements, as well as the geometrical ratio of the panel (height/length). On the basis of the numerical results, a capacity formulation has been proposed, which takes into account the steel distribution in the masonry panel. The obtained outcomes revealed that the strength increase achievable by adopting the studied reinforcement system could be compared to the efficiency of a reinforced masonry wall of new construction and it is strongly influenced by the geometrical ratio of the wall, as well as the steel distribution.

Automated summary

The current research focuses on investigating the efficiency of a steel-based reinforcement system suitable for existing masonry walls through numerical and analytical studies. By conducting experimental tests and numerical simulations, a design criterion has been proposed demonstrating that the strength increase achievable by adopting this reinforcement system can be comparable to that of a new construction masonry wall.