This study investigates the effectiveness of steel slag and polypropylene (PP) fiber reinforcement in improving the progressive collapse resistance of masonry-infilled reinforced concrete (RC) frames. Experimental tests were conducted on five frame specimens under graduate lateral loading monotonic lateral displacement control, complemented by limited finite element validation. Experimental tests were performed on four reinforced concrete (RC) infilled frame models and compared with a control RC infilled frame model under gradual lateral loading. These improved models are divided into two categories: those reinforced with steel slag or P.P fibers in the concrete mixture, and those reinforced exclusively in the mortar mixture between the bricks in the wall. In addition to performing numerical analysis of the experimental models using the Abaqus finite element software and studying some variables, including P-Δ relationships, as well as crack patterns and strain values. The finite element analysis aligns closely with the experimental findings, demonstrating significant agreement especially with regard to ultimate load capacities and failure modes, thus enabling the studying additional variables subsequently, given the considerable expense associated with laboratory experiments. The results indicate that the addition of P.P fibers result in more effective mortar or concrete mixes than steel slag addition, resulting in significant improvements in strength, toughness, ductility and crack pattern. Despite frequent cracks, no breakage was observed due to fibers acting as threads connecting particles, preventing separation during loading and collapse. As a result, the compressive strength of concrete increases by 30.4% and 60.9%, while the tensile strength improves by 60% and 140% with the addition of slag and P.P. fibers, respectively, compared to control mixtures. Polypropylene fiber-reinforced models exhibit superior resistance to collapse under progressively applied lateral loads, making them the most effective of the configurations tested. In general, the addition of these reinforced materials extends the service life of the building in the event of such a collapse and provides an additional opportunity to mitigate its effects.