This paper presents the experimental results of section enlargement effects on prismatic reinforced concrete members. 125 by 200 mm reinforced concrete members with a compressive strength of 20.3 MPa reinforced with D12 steel bars having a yield stress of 335 MPa situated in the tension and compression area, were produced. Two specimens were prepared, the first functioning as the control element and designated as the Control Beam (CB). The second strengthened with a section enlargement using Self-Compacting Concrete (SCC) marked as the Strengthened Beam (SB). The SCC had a 28-day compressive strength of 23.9 MPa. The dimensions of the enlarged beam were 200 by 300 mm. The two specimens CB and SB were tested with a two-point loading system. Based on the tests data, the load–displacement and moment–curvature relationships characterizing the beams were generated. From the results it was concluded that the enlargement affected the load-carrying capacity and stiffness positively. The SB member had a six times higher moment capacity, while the stiffness performance was enhanced seven times when compared to the CB specimen. On the other hand, it was also demonstrated that the ductility of the SB decreased as a consequence of the increase in span-to-depth ratio. The study was expanded based on the rational analyses to evaluate the influence of the additional tensile steel and concrete strength ratio of the enlarged section. Copyright © 2020 Praise Worthy Prize - All rights reserved.