SUMMARYThis paper proposes a new analytical model for masonry-infilled R/C frames to evaluate the seismic performance considering R/C frame-infill interactions. The proposed analytical model replaces masonry infill with a diagonal compression strut, which represents distributed compression transferred between frame and infill interfaces. The equivalent strut width is presented as a function of the frame-infill contact length, which can be evaluated by static equilibriums related to compression balance and lateral displacement compatibility at the frame-infill interfaces. The proposed analytical model was verified through comparisons with experimental results obtained for several brick masonry-infilled R/C frames representing a typical R/C building with nonstructural masonry infill in Indonesia. As a result, good agreements were observed between the experimental and analytical values of the lateral strength and ductility of the infilled frames. The seismic performances of two earthquake-damaged R/C buildings with different damage conditions were evaluated considering infill effects by applying the proposed analytical model. Consequently, the nonstructural brick masonry infill significantly affected the seismic resistances of the buildings, which seemed to lead to differing levels of damage for each building. These results indicate that the proposed analytical model can be an effective tool for more precisely screening earthquake-vulnerable existing R/C buildings in Indonesia.