About the influence of the infill panels over the collapse mechanisms actived under pushover analyses: Two case studies

A large number of research studies have been recently devoted to the modelling and analysis of mulled RC framed buildings under seismic actions, and the significant role that the infill plays in the overall structural performance is by now a well acknowledged result. In particular, the extension of N2 method to mulled frame allows the appraisal of this contribution within the framework of a non linear static analysis. The present paper reports the results of the non linear static assessment performed for two RC existing buildings located in a high seismic hazard area. Both building are characterized by regularity in plan and elevation, but while the first one is a low rise construction, the second one is relatively tall (7-storey). Thence, there is the possibility of considering two different and interesting situations. For the two case studies, moreover, a complete investigation protocol was previously carried out, providing a detailed experimental information about the materials (concrete, steel reinforcements, masonry mull). Numerical analyses were performed by using spatial models, both for the bare frames and for the infilled frames, in order to appraise the variation of the structural capacity because of the interaction of the infills with the RC elements.