Seismic Response of Infilled RC Frames Designed Considering Local Wall-Frame Interactions

It is well known that the interactions between the frames and the infill walls can have significant effects on the seismic response especially for low-rise frames. On one hand, the infill walls can increase the strength and stiffness of the frame, which result in higher seismic resistance. On the other hand, the local interaction between the infill wall and the frame due to the compressive diagonal strut in the infil wall can lead to increased shear demand in the column. This can lead to an undesirable failure mode such as shear failure of the column leading to loss of frame strength at low drift levels. One appealing approach for considering infill walls is by preventing all the undesirable failure modes induced by the wall-frame interaction while not considering the advantages from the increase in strength and stiffness due to the infill wall. Based on this approach, infilled frames are analyzed and designed as if they were bare frames as commonly done in design practice. Columns are then checked for increased shear demand at the local level to counteract the
adverse effects of the infill walls. In this study, one such design strategy is investigated. The design approach is first presented including a method to estimate the increased shear demand in the column due to local wall-frame interaction. The approach was used to design RC frames with infill walls located in Thailand. The performance of these frames was assessed using nonlinear static and dynamic analyses. The performance of the frames and the failure modes were discussed in comparison to those of the frames designed without considering the local interactions. The merit of this approach as well as its limitations were discussed and summarized.