An innovative cladding panel connection for RC precast buildings

Recent Italian earthquakes highlighted some critical issues of mechanical devices usually utilized to fasten reinforced concrete cladding panels to precast structures. These devices were often designed to uncouple the displacements of cladding panels and the frame structure. Unfortunately, during the last earthquakes, the cladding-to-structure connections did not perform as expected, and in most cases, they failed causing the overturning of cladding panels. The paper presents results of a wide experimental campaign on both commercial and innovative mechanical cladding-to-structure connections, both for vertical and horizontal panels. Tests were performed in the Structures and Materials Testing Laboratory of the Department of Civil and Environmental Engineering of Florence, where a specific and original setup was designed to perform dynamic cyclic tests, under different load conditions. Commercial connections showed a hysteretic behaviour until the collapse, due to the flexural failure of the strap or to the failure of the anchor channel fixed to beams or columns and the expulsion of the hammer-head screws. Proposed innovative connections, especially those used for vertical panels, proved to be able to uncouple in-plane horizontal displacements of panels and the structure, as expected in their design. Moreover, no significant damage was detected in these connections during tests, as friction forces were very low.