<p>Extensive studies have been conducted on masonry-infilled reinforced concrete (RC) frames to investigate the influences of infilled walls on frames. Equivalent strut models and the force-displacement relationships of infills have been proposed to simplify the seismic performance analysis of masonry-infilled RC frames. However, the existing force-displacement relationship for equivalent strut models oversimplifies the influence of the material properties of infills and the constraint of RC frames. In this paper, the discrete element method (DEM) was adopted to simulate the seismic performance of infilled masonry walls in RC frames. Three DEM-based RC frame models and six masonry-infilled RC frame models were verified by ultimate bearing capacities, initial stiffnesses, hysteresis curves and failure modes from experimental literature. Based on validated models, a parametric analysis was performed to investigate the factors that influence the seismic behaviour of infills, considering the constraint effect of frames. Subsequently, a force-displacement relationship was proposed to predict the seismic performance of infilled walls in RC frames, and validated by equivalent strut models in SAP2000. It was noted that the equivalent strut models tended to underestimate the stiffness and strength of RC frames, especially for large deformations. Compared to the results of experiments, DEM simulations and simplified models, this study recommended the simplified equivalent models for rapid prediction of seismic performance while advocating the DEM models for failure or collapse analysis of RC frames.</p>