Traditional and innovative systems for injected anchors in masonry elements: Experimental behavior and theoretical formulations

Abstract

Over the last recent years, the interest in the use of injected anchors as a strengthening method for avoiding out-of-plane mechanisms in existing masonry buildings has been strongly increased. Common traditional techniques made by steel bars are currently integrated by alternative ones based on the use of innovative materials as Fibre Reinforced Plastic (FRP) bars. The paper firstly focuses on a critical analysis of several strength models available in literature for anchors embedded in both concrete and masonry substrates. Moreover, the analysis of literature about injected anchors in masonry elements has been completed by the collection of experimental results of pull-out tests carried out by several researchers. The collected database is also enriched by the results of pull-out tests directly carried out by the Authors and described in detail in the paper. Then, the reliability of the existing strength models into predict the pull-out forces has been investigated by means of comparisons with the available experimental results. Finally, according to the ‘design by testing’ approach, regression analyses have been carried out on the whole database in order to assess new formulations taking into account the most important parameters influencing the performance of injected anchors made of both traditional and innovative materials.