Experimental validation of dissipative anchor devices for the seismic protection of heritage buildings

In the last decades, considerable improvements have been achieved in the seismic protection of buildings thanks to the enhancement of structural ductility and energy dissipation systems; nowadays both concrete and steel frames are indeed able to provide advanced seismic performances. Nevertheless, historic centres are still considerably affected by earthquakes (L’Aquila, 2009) since extensive retrofit is lacking, or it is applied by techniques that rely on the increase of stiffness and strength capacity, without due care for precious finishes. In order to address the lack of specific passive systems for heritage buildings, the authors have developed two dissipative devices, one based on steel plasticity, the other on friction, that can be integrated in traditional steel anchors and installed within the masonry at the joints of perpendicular walls, where out-of- plane mechanisms are likely to form due to poor quality connections. The experimental validation of prototypes was carried out within the framework of a Knowledge Transfer Partnership between the University of Bath and Cintec International Ltd: pseudo-static and dynamic tests were performed to characterise the performance of the isolated devices, while pull-out tests were carried out in masonry panels with modest shear capacity for comparison with standard steel anchors; Finite Element modelling was as well undertaken, calibrating results with data from tests. The paper discusses experimental and computational results, focusing on the friction-based prototype; the need for further theoretical work concludes the paper.