KRŽAN, META1; MASIA, MARK2; BOKAN-BOSILJKOV, VIOLETA3; BOSILJKOV, VLATKO4

1 Research Assistant, PhD Student, University of Ljubljana, Faculty of Civil and Geodetic Engineering, Ljubljana, Slovenia, meta.krzan@fgg.uni-lj.si

2 Associate Professor, PhD, The University of Newcastle, School of Engineering, Centre for Infrastructure Performance and Reliability, Callaghan, Australia, Mark.Masia@newcastle.edu.au

3 Associate Professor, PhD, University of Ljubljana, Faculty of Civil and Geodetic Engineering, Ljubljana, Slovenia, violeta.bokan-bosiljkov@fgg.uni-lj.si

4 Associate Professor, PhD, University of Ljubljana, Faculty of Civil and Geodetic Engineering, Ljubljana, Slovenia, vlatko.bosiljkov@fgg.uni-lj.si

For monumental buildings, retrofitting following seismic events with less invasive techniques is of paramount importance. Since walls are typically multi-leaf stone masonry, apart from crack grouting, preventing leaf separation and limiting out-of-plane deformations should also be considered. This paper presents an experimental investigation of the effectiveness of various retrofitting measures for this type of masonry under compression and in-plane lateral loading. Nine previously damaged three-leaf stone masonry walls were retrofitted and retested under the same boundary conditions. The aim was to use compatible materials and to minimize aesthetic impact. All cracks were grouted with lime-cement grout and some walls were additionally strengthened with near surface mounted (NSM) glass cords, inserted into horizontal mortar joints in various dispositions. For some walls glass cords were also inserted transversally providing connections between the leaves. Under shear loading, grouting of cracks restored the walls’ initial strength and displacement capacity. NSM glass cords in some dispositions increased the displacement capacity and in some cases, depending on the boundary conditions, also changed the collapse mechanism.

Keywords: Seismic retrofitting, NSM, glass cord, grouting, multi-leaf stone masonry, in-plane shear tests, compression tests, historic masonry, heritage buildings