This paper presents a preliminary investigation on the local shear demand in masonry-infilled reinforced concrete (RC) frames subjected to nonlinear dynamic loads. A refined numerical model is developed in the STKO/OpenSees environment to simulate a full-scale experimental test, capturing the local interaction effects between infill panels and the surrounding frame. The numerical model is calibrated to replicate the global response observed during the shaking table test of a three-story RC building. The study aims to extrapolate and quantify the additional shear demand induced at the column ends due to the presence of infill walls under seismic excitation. A preliminary comparison is also made between the refined numerical outcomes and a simplified analytical formulation available in the literature for predicting local shear demand. Initial results indicate that this model may be applicable under nonlinear dynamic conditions, although further validation is needed. These findings support the potential integration of such predictive tools in seismic assessment and highlight the crucial importance of accurately modelling local infill-frame interaction to ensure reliable structural design and evaluation.