<p>Masonry infilled reinforced concrete (MI-RC) frames are widely used in building construction, particularly in seismically active regions. Although the masonry infill (MI) is conventionally treated as a non-structural element, its interaction with the surrounding RC frame significantly governs the post-yield lateral load response of the structure. This study presents a calibrated non-linear finite element (FE) analytical framework, implemented in the commercially available software SAP2000, and validated against experimental results of geometrically scaled half-scale MI-RC frame models subjected to in-plane reversed cyclic lateral loading. A modified bi-linear stress-strain idealization, derived by inverse calibration against experimental backbone curves, was adopted to incorporate interfacial non-linearities including MI-frame bond deterioration and masonry heterogeneity into effective material constitutive parameters. The validated model was subsequently applied to perform monotonic static non-linear (pushover) parametric studies on full-scale, three-bay, five-storeyed exterior MI-RC frames with and without central openings in the infill panels. Frames strengthened with geo-fabric reinforcement at the MI-RC interface were also investigated. Within the parametric scope studied, results indicate that geo-fabric strengthening enhances lateral load capacity by approximately 40–45% relative to conventional MI-RC frames. A preliminary trend of near-linear reduction in lateral capacity of approximately 3% per 1% increase in central opening area was observed for the opening ratios examined. Top storey drifts computed from non-linear pushover analysis at ultimate capacity significantly exceeded those from linear static analysis. These findings provide practical insight into the monotonic pushover response of the specific MI-RC configurations studied and support capacity-level assessment for performance-based seismic design.</p>