Masonry infill construction and retrofit technique for the infill-frame interaction mitigation: Test results

The paper describes the set-up and testing of an innovative construction technique for masonry infill, which can provide a flexible and predictable in-plane response to the infill inside the frame, together with a stable and reliable out-of-plane response. The design strategy is to downgrade the infill reaction inside the structural frame thanks to a dramatic reduction of the masonry in-plane stiffness. The infill is partitioned by vertical planks (or equivalent beams) into sub-panels, free to relatively slide and rock on their toes. The planks connected to the beams provide the necessary out-of-plane stability. The solution was tested for application in both new and existing infills and construction details are discussed. A comparison is also presented with the performance of two infills, one continuous and one with horizontal sub-panels, previously tested under the same conditions. The observed infill downgrade makes practically negligible the infill-frame interaction and the post-earthquake masonry damage.