Effect of infill wall configurations on the behaviour of regular and irregular rc frames in elevation

In this study, regular and irregular in elevation reinforced concrete frame structures with different masonry infill wall configurations were investigated. The case study structure with seven storeys and four bays was designed as regular frame model (without any setbacks) while the other four structures had the same configuration in the first storey and larger setbacks in upper ones. Thus, one regular and four irregular frame models were evaluated with and without three infill configurations, namely, partially infill and fully infill. For the partially infill, two cases were adopted as dou-ble and quadruple bay infill. In both cases, the infill was omitted at ground floor. The diagonal strut approach was assumed for modeling the infill walls. FEMA 306 guide-lines were utilized to determine the width of equivalent strut. Nonlinear pushover and time history analysis, in which nonlinear behavior is assumed to observe within the frame elements at concentrated plastic hinges, was performed to determine the effects of masonry infill walls on the seismic response of different frames. The finding of the study indicated that the presence and arrangement of infill walls remarkably altered the strength and stiffness as well as the collapse mechanisms of both regular and especially irregular case study structures.