Seismic Enhancement of Masonry-Infilled Non-ductile Reinforced Concrete Frames by Separating Wall from Columns

Abstract

An experimental study on the structural performance of a retrofitted masonry-infilled non-ductile reinforced concrete (RC) frame is presented. One ¾ scaled model of a single bay, single story, non-ductile RC frame with masonry infill wall was tested under lateral cyclic loading and constant vertical load. The masonry infill wall was detached from the columns and steel brackets were used to transfer the forces from the wall to the beams, thereby totally eliminating the transfer of large infill strut force to the columns. The retrofitting scheme utilized greatly enhanced the performance of the frame by increasing the overall capacity and story drifts at different performance levels approximately 6 times compared to those of the non-retrofitted specimen. Moreover, severe shear damage in the columns was totally eliminated. For this retrofitting method, the width of the infilled panel had a significant effect on the behavior and load resistance capacity of the frame. The analytical result showed that the lateral strength of the masonry wall decreased and the bending moment in the RC beam increased, when the width of the wall was reduced. Therefore, the strength of the surrounding frames must be investigated prior to properly select the width of the infill panel.