Openings in infills with horizontal sliding joints: a parametric study to support the design

In the present paper a numerical study is reported, aimed at investigating the role of openings in the in-plane response of infilled RC frames when masonry infills with sliding sub-panels are adopted. Such innovative infills are meant to reduce post-earthquake damage and infill-frame interaction, with respect to traditional solid masonry infills. Their study was carried out mainly on the fully infilled configuration, and limited information is available about its response in presence of an opening. In the paper focus is made on the interaction of the infill with both the surrounding frame and with the specific post placed at the opening side, which is essential to confine the infill and protect the opening fixtures. The adopted numerical model is calibrated on the experimental results of a test performed on a real scale infill wall with horizontal sliding joints and a full-height opening on a side. A parametric study is carried out to investigate the influence of different design parameters. In detail, the focus is placed on the stiffness of the post and on the geometry of the infill (in terms of position of the opening, infill length and sliding joint configurations). The obtained results show the beneficial effect of the post deformability in reducing the infill-frame interaction, with a significant reduction of the shear action exerted on the frame columns and on the post itself. Moreover, the obtained results allowed to define some preliminary recommendations for the design of the infill and of the post at the opening side.