Performance-based interpretation of in-plane cyclic tests on RC frames with strong masonry infills

In line with the current European building practice, clay masonry infills are commonly adopted for the construction of enclosures and partitions in RC frame structures. In order to improve further the understanding of the seismic response of masonry infills in newly designed RC structures, within the scope of a systematic numerical and experimental research program, the in-plane experimental response of external masonry infills constructed with tongue and groove clay units has been studied. Particular attention has been devoted to the infill performance, the related damage distribution, the lateral stiffness, strength and dissipation capacity and a possible definition of performance limit states for future developments in the current design approach. This paper reports the framework and discusses the results of in-plane static cyclic tests on full-scale, single-storey, single-bay RC frame specimens with strong masonry infills with and without opening designed following European seismic design provisions, carried out at the laboratory of the Department of Civil Engineering and Architecture of the University of Pavia. Based on the observations during the tests, drift levels at the different limit states have been evaluated, with the attainment of large values for the solid specimen (0.30%, 0.50% and 1.75% at the operation, damage limitation and ultimate limit state, respectively), but lower performance for the panel with opening. The experimentally obtained lateral stiffness and strength have been compared with the results of some of the most common analytical models based on single diagonal equivalent strut, underlining the formulations that better fit the test outcomes.