Response evaluation of reinforced concrete frames with masonry infill walls through nonlinear static analysis

The structural response of reinforced concrete (RC) buildings subjected to lateral load is noticeably influenced by the masonry infill walls because of their contribution to strength and stiffness. In the literature, there are several modelling approaches for the infill walls. But, they provides different results. In this study, the equivalent diagonal strut model was utilized. The key parameter of this strut is its equivalent width. In the first part of the study, different expressions exist in literature for computing the width of compressed diagonal strut were examined. Among them, the Paulay and Priestley relationship which gives average value was chosen for modelling of the masonry infill walls. In the second part of the study, a sensitivity analysis was performed by considering 2, 4, 6 and 8 storey RC bare frames and those with infill walls. Four different infill wall frame configurations, namely, fully infilled frame, fully infilled-soft storey frame, interior bay infilled frame, and interior bay infilled-soft storey frame, were adopted. Single-strut and three-strut models for simulating wall panels were employed in all infilled frames. Thus, a total of 36 different RC frame models (covering 4 bare and 32 infilled frames) was evaluated through nonlinear static analysis in order to appraise the infill wall effect on the overall response of the case study frame buildings. The results of the analysis showed that the arrangement of the infill panels over the elevation of the frame had considerable effect on the performance of the structures. Additionally, the serious capacity reduction was observed particularly for the case of infills discontinued at the ground storey.