Investigating the effect of infill walls in creating short columns in concrete frames (a case study

Owing to the common use of infill walls in conventional buildings, it is a practical and important topic to investigate the effect of infill walls on the behavior of structures during earthquakes. One of the disadvantages of infilled frames is the presence of large window openings in some of the reinforced concrete frame buildings, which results in the short column phenomenon. The part of the column that is adjacent to the wall is almost integrated with the wall and leads to a reduction in the height of the column. Therefore, the lateral stiffness increases considerably. With increasing stiffness, the lateral force applied to the column also increases. In this study, a 4-story, 3-span reinforced concrete model with a different arrangement of infill walls in the stories and considering short walls on the ground floor, the short column phenomenon has been investigated in ETABS software. Also, the seismic capacity of the structure has been calculated by valid methods based on the capacity spectrum method proposed by ATC40. The results indicate that with increasing stiffness, the maximum shear force applied to the column due to the presence of the infill wall under the designed earthquake load will increase by about 50% compared to the frame without the infill wall. Furthermore, the amount of stiffness difference in the frame with and without infill wall in the analyzed models is about 70%, which can prevent irreparable damage by predicting this event and proper design.