Five corbels composed of reinforced concrete were tested for this investigation with identical dimensions and a constant concrete compressive strength of 30 MPa. The specimens were tested under monotonic loading using a single-point loading system. One specimen was used as a control specimen without strengthening, designated as (D-C-F30-0.2). Hollow steel sections (HSS) with various strengthening configurations and shear span-to-depth ratios were used to reinforce the remaining four specimens. The first strengthened specimen, designated as (D-P-SS-F30-0.2), was reinforced in the horizontal and inclined strut regions using hollow steel sections to enhance the compressive force-transfer mechanism within the corbel. The second specimen, designated as (D-P-TSS-F30-0.2), was strengthened in the horizontal and inclined strut regions in addition to the tie region at a ratio of 0.2. The third specimen, designed as D-P-TSS-F30-0.3, employed the same strengthening configuration with a ratio of 0.3 to examine the impact of increasing the shear span-to-depth ratio on the structural response. Similarly, the fourth specimen, designated as (D-P-TSS-F30-0.35), was strengthened in the horizontal and inclined strut regions together with the tie region, with a ratio of 0.35. The experimental program was designed to evaluate the influence of the strengthening configuration and the variation in the ratio on the structural behavior of reinforced concrete corbels in terms of crack propagation, stiffness, load-carrying capacity, toughness, ductility, and failure mechanism.
