Abstract
This paper examines the experimental flexural performance of the strengthening composite concrete asymmetrical castellated steel beam of double channel shape by connecting two castellated hot rolled steel channels back-to-back using bolts along its length to obtain a built-up I-shaped form with a new total beam depth heightened by 52.4%. This research tested four specimens: the first was a reference specimen without any strengthening techniques; the second was strengthened with RPC (Reactive Powder Concrete) in the steel web region; the third was strengthened by RPC reinforced with a lacing rebar. Also, this study investigated the welding effects in web posts for the top and bottom parts of the castellated steel in the fourth specimen. All specimens were tested under simply supported conditions by applying two-point static loads on the concrete deck slab of the composite beams. The ultimate load deflection, stiffness, ductility, energy absorption capacity, and failure mode were investigated and discussed. According to the experimental results, the ultimate load capacity increased 24.01% and 48.34% in the second and third specimens, respectively, with increased stiffness, ductility, and energy absorption capacity compared with the first specimen. In contrast, the ultimate load capacity decreased by 11.02 % in the fourth specimen (strengthening without welding in web posts), reducing stiffness and ductility compared with the first specimen (reference).