Pseudo-dynamic tests on full-scale two storeys RC frames with different infill-to-structure connections

Field surveys showed that the fabrication of infill, with particular emphasis on the connection with the surrounding reinforced concrete (RC) frame, may have a significant influence on the global response, earthquake damage and on the actions transmitted to the surrounding RC members. This study reports and discusses the outcomes of an experimental program on three two-storeys full-scale infilled RC frames varying the concrete strength and infill-to-structure connection. The specimens were subjected to pseudo-dynamic tests at increasing intensity to characterize the frame response and the related damage states. The results showed that the strength and stiffness of the frame increase by increasing the infill-to-structures connection. The enhanced connection allows to have a better loading transfer from the structure to the infill with a strength increase ranging between 10% and 30%. This resulted in a reduction of the displacement demand and in an increase of the shear force transmitted to the top of the column. The results are compared with the damage observed during post-earthquake field survey at building level and with available fragility functions showing a good matching. A non-linear FEM model is proposed to capture the lateral response of the tested frames and the results are compared and discussed. The comparison outlines the reliability of a three-strut model to accurately reproduce the infill response and the shear actions transmitted at the top of the columns.