Seismic retrofit of a precast RC building with bidirectional rotational friction dampers (BRFDs) in Northern Italy

Precast RC structures have been widely used in Italy during past 70 years and mainly adopted to host industrial and commercial activities. For these structures, quite common features are poor connections between structural elements because many of them were designed for gravity loads only. Moreover, one of the major sources of collapse of precast structures, especially when beams are simply supported by columns with frictional bearings, is the vertical component of the ground motion in near-fault conditions, which can strongly reduce horizontal restrains. Besides people’s safety requirements, the preservation of high-value facilities and stocks demands the adoption of effective retrofit techniques for earthquake risk mitigation and community resilience improvement. This study presents the application of a novel Bidirectional Rotation Friction Damper (BRFD) as innovative retrofit solution for a sustainable upgrading of precast RC structures seismic performances, in particular an industrial warehouse for storage hosting 14-meters-high tanks in Forlì, Italy. The effectiveness BRFDs has been investigated using Nonlinear Time History Analysis (NLTHA). The designed retrofit solution provides a global improvement of the seismic performance of the building, preventing any structural and non-structural damage with low costs. The major benefit of BRFDs application respect to traditional techniques is the reduction of the number of devices and their steel connections to RC members, due to the innovative bidirectional feature, avoiding the foundations retrofitting, which leads to significant savings.