Preliminary results on the tensile capacity of steel anchors in brick units of different materials

High strength steel bars are widely used for the strengthening of masonry buildings, in particular to improve the connection between different structural elements, such as orthogonal walls and multi-leaf walls. A particular type of steel connector is the twisted bar, which due to its particular shape works as a self-threading screw, anchoring to the support material without any binder. The effectiveness of such technique mainly relies on the bond between the bar and the substrate, where adhesion, mechanical interlocking and friction play an important role. In this paper, a preliminary experimental study on pull-out behavior of twisted steel connectors inserted in brick units of different materials that can be commonly found in existing masonry buildings in Italy and in Europe is presented. Additionally, mechanical characterization of the materials is conducted to understand the influence of the compression strength and elastic modulus on the adhesion between the connector and the substrate. Preliminary results show that the pull-out response strongly depends on the mechanical properties of the substrate material.