EXPERIMENTAL AND NUMERICAL IN-PLANE SEISMIC BEHAVIOUR OF AN INNOVATIVE STEEL REINFORCEMENT SYSTEM FOR URM WALLS

An experimental campaign, followed by a numerical research, aimed at evaluating the in-plane seismic behaviour of an innovative steel modular system (named “Resisto 5.9”, designed by Progetto Sisma s.r.l.) for the reinforcement of load-bearing masonry walls, has been performed at the EUCENTRE Foundation in Pavia. Different masonry typologies, selected among the most common solutions in Italian existing buildings, were considered in this study. In this paper, the results related to a solid clay bricks masonry, assembled using lime mortar in “header bond” pattern, are reported. A complete mechanical characterization of units, mortars, masonry typologies and of the strengthening system components (i.e. steel elements and anchors) has been carried out. In-plane cyclic pseudo-static tests were then performed on full-scale specimens to investigate the influence of the proposed reinforcement system on the lateral in-plane response of the walls, compared to their unreinforced conditions. The main parameters which characterized the cyclic behaviour of the masonry piers, i.e. elastic stiffness, lateral strength and displacement capacity, were analysed in relation to the achieved damage mechanism. The numerical study of the research consisted of a series of parametric non-linear analyses on advanced discontinuous models based on the Distinct Element Method (DEM). Different wall dimensions, vertical load levels and boundary conditions, in addition to those tested experimentally, were considered. Moreover, the numerical campaign was also extended varying the bond pattern and the mechanical properties with respect to the experimentally tested solutions. In this paper, the results of the experimental tests on solid brick masonry together with the calibration of the related numerical DEM models were reported.