Issue 29

L. Contrafatto et alii, Frattura ed Integrità Strutturale, 29 (2014) 196-208; DOI: 10.3221/IGF-ESIS.29.17 196 Focussed on: Computational Mechanics and Mechanics of Materials in Italy Prediction of the pull-out strength of chemical anchors in natural stone L. Contrafatto University of Catania – Italy. Department of Civil Engineering and Architecture loredana.contrafatto@dica.unict.it R. Cosenza University of Catania – Italy. Laboratory of Structural and Material Testing. renato.cosenza@studium.unict.it A BSTRACT . The applicability of some numerical models for the prediction of the failure mechanism and of the bearing capacity of post-installed threaded rods chemically anchored in basalt, sandstone and limestone is investigated, as well as the reliability of theoretical formulations conceived for concrete. The numerical predictions, performed by means of engineering structural analysis software and advanced numerical codes, are compared with the results of an experimental research related to chemical anchors in natural stone. The minimum embedment depth for such fastening system is identified. K EYWORDS . Adhesive anchor; Epoxy resin; Threaded rods; Sandstone; Basalt; Limestone. I NTRODUCTION asonry was in the past, and is, today, one of the most commonly used materials throughout the world for the construction of low rise buildings. The stonework is largely widespread in different countries and despite the variety of materials and techniques used, it has recurring problems regarding both the vulnerability to seismic actions and the applicability of reinforcement techniques. There are many techniques that can be implemented on masonry buildings. In particular, in the context of the retrofitting of existing buildings, a great development has been achieved with the use of anchoring systems. Chemical anchoring systems are commonly used in plain or reinforced concrete structures but also in structures in lightweight material, such as wood and brick, and in masonry constructions to rigidly couple different structural elements. A variety of metal elements are usually used, normally steel elements such as stirrups, reinforcement bars, threaded rods. The adhesive component of the system is generally resin. Although the specific legislation on the architectural heritage does not allow the use of resin on historical and monumental buildings, but suggests the usage of special mortars, there exists a lot of cases in which the use of chemical anchoring is more suitable than mortar, especially in the case of anchoring systems on rocks or high resistance supports. Such is the case of all the masonry buildings that are not under a preservation order or listed buildings. While a number of studies, both theoretical and experimental, concerns the behavior of concrete anchors, in terms of pull-out strength and anchor depth determination, as reported in [1-6], the lack of data concerning the behavior of chemical anchors in natural stone is incontrovertible and theoretical formulations in the literature valid for concrete are often not applicable, depending on the nature and quality of the stone type. M