<![CDATA[Reinforced concrete cantilever beams with long spans are prone to excessive deflection, which may adversely affect structural performance and safety. This study aims to analyze alternative strengthening methods for reinforced concrete cantilever beams in a villa building where the cantilever length was extended up to 3.65 m during the construction stage, resulting in deflections exceeding the allowable limits. The research employed a quantitative approach using three-dimensional structural modeling with ETABS software. Existing structural conditions were identified through non-destructive testing, including hammer tests and rebar scanning, to determine the residual concrete strength and reinforcement configuration. The analyzed strengthening measures constitute an integrated strengthening package consisting of first-floor column jacketing, the addition of second-floor columns, and the enlargement of second-floor cantilever beam dimensions as a unified structural system. Structural performance was evaluated in terms of deflection, bending moment, shear force, and axial force before and after strengthening. The analysis results indicate that prior to strengthening, the cantilever beam deflections did not satisfy the allowable deflection criteria. After strengthening, the deflections were significantly reduced by 22.8% at the roof level and 56.8% at the second-floor level, meeting the allowable deflection requirements. In addition, the internal force distribution improved and the supporting capacity of the structural elements increased. Therefore, the proposed strengthening alternatives are proven to be effective in enhancing the structural behavior of long-span cantilevered reinforced concrete beams.]]>
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