Seismic strengthening of existing URM structures through CLT elements: Numerical analysis of the application of a novel intervention technique

The retrofit of existing masonry buildings plays a relevant role in the Italian building context, both for preservation and requalification of the cultural and architectural heritage. Historically, timber has been widely used in unreinforced masonry (URM) buildings, mainly for horizontal structures. In recent years, the use of timber in the retrofit of existing buildings has gained an increasing interest for the improvements of both structural and energetic performances. Indeed, wooden elements present good hygrothermal properties and, thanks to their lightweight and stiffness, they are suitable for the seismic improvement of masonry buildings. The aim of this paper is to numerically investigate the seismic strengthening of existing URM structures by means of cross laminated timber (CLT) panels, evaluating the coupling degree of the timber-masonry integrated system. The investigation was carried out through a finite element modelling. First a parametric local model of a CLT-masonry coupled wall was calibrated with literature experimental data. Then, the study was extended to a XVII-century URM building located in the Italian Alpine region (Roana, Vicenza province). Non-linear static analyses were carried out in order to assess the local and global behavior of the URM-CLT system and its potential benefits. Results suggested a seismic capacity improvement due to shear strength increase and global weight reduction.