Corbels are structural connections between beams and columns that provide support to slabs and, in some cases, act as short cantilever beams. A compression strut is typically formed within the corbel, where failure often initiates. Since this strut functions as a short-concealed column, its strength primarily depends on the compressive strength of the concrete and the a/d ratio. This study aims to investigate the influence of different concrete compressive strengths on the behavior and ultimate load capacity of corbels, as well as the influence of geometry on corbel resistance. Eight specimens were cast and tested to examine these parameters. Four models with varying mixes were investigated, and the gained concrete compressive strengths (15, 20, 25, and 30 MPa) were considered, while the other four specimens investigated the influence of varying the a/d ratio as (1, 0.75, 0.5, and 0.35). The results indicated that the ultimate load increased by 11.5%, 37%, and 85% for specimens with compressive strengths of 20, 25, and 30 MPa, respectively, compared to the specimen with 15 MPa. Additionally, the concrete strength had a significant impact on the initial cracking load (or appearance of the first crack), indicating a direct relationship between corbel performance and material strength. Additionally, the corbel strength rises when a/d is minimized. In terms of deflection at failure, specimens with higher a/d ratios showed larger deflections, whereas specimens with lower a/d ratios displayed stiffer behavior and smaller deflections at failure.
