On Mechanical Behavior of Metal Anchors in Historical Brick Masonry: Testing and Analytical Validation

Abstract

The repair and strengthening of historical masonry buildings is a fundamental aspect in the conservation of the built cultural heritage. Temporary shoring or strengthening are often used and, usually, involve the introduction of new metallic elements. The connection between the original substrate and the new elements must be analyzed carefully to prevent further damage to the building. This paper presents a study on the mechanical behavior of metal anchors applied to brick masonry walls. An experimental campaign is developed, and a series of pull-out tests are carried out on masonry walls built in a laboratory with natural hydraulic lime mortar and low mechanical strength bricks. Two groups of tests are conducted, namely, with the actuator in the direction of the anchor axis and with the actuator inclined with respect to the fastener axis. Moreover, two types of anchoring systems are used, namely, adhesive (chemical and cementitious grout) and mechanical anchors. The experimental results are compared to predictive analytical formulas available in the literature for estimation of the ultimate load capacity, according to the type of failure. From the comparison between experimental and analytical values, it is proven that the analytical formulation originally developed for concrete substrates cannot be directly extrapolated to brick masonry cases, and specific predictive formulas should be developed. The presented research can be used to select the most efficient anchoring system for strengthening and retrofitting of historical brick masonry structures.