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This paper presents an experimental study on 18 specimens, including 15 polyvinyl chloride (PVC)‐carbon fiber‐reinforced polymer (CFRP) tube confined reinforced concrete beams with longitudinal CFRP sheets (PCT‐RCBs‐LCS) and 3 PVC‐CFRP tube confined reinforced concrete beams (PCT‐RCBs). The effects of five studied parameters, such as longitudinal reinforcement rate (ρs$$ {\rho}_{\mathrm{s}} $$), concrete strength grade (Sc$$ {S}_{\mathrm{c}} $$), width (df$$ {d}_{\mathrm{f}} $$) and number (nf$$ {n}_{\mathrm{f}} $$) of longitudinal CFRP sheet, and specimen dimensions (Ds$$ {D}_{\mathrm{s}} $$), on the failure mode and flexural capacity are investigated. The PCT‐RCBs‐LCS with lower df$$ {d}_{\mathrm{f}} $$ and nf$$ {n}_{\mathrm{f}} $$ fail by the breakage of the PVC tube and the fracture of longitudinal CFRP sheets. Conversely, the cracking of PVC tube dominates the damage of the PCT‐RCBs‐LCS with higher df$$ {d}_{\mathrm{f}} $$ and nf$$ {n}_{\mathrm{f}} $$, while the longitudinal CFRP sheets are not broken. The introduction of longitudinal CFRP sheets can significantly improve the flexural capacity. The ultimate flexural capacity of the PCT‐RCBs‐LCS increases as the ρs$$ {\rho}_{\mathrm{s}} $$, sc$$ {s}_{\mathrm{c}} $$, df$$ {d}_{\mathrm{f}} $$, nf$$ {n}_{\mathrm{f}} $$ or Ds$$ {D}_{\mathrm{s}} $$ increases. In addition. considering the influence of RC beam section shape, a model for predicting the ultimate flexural capacity of the PCT‐RCBs‐LCS is proposed based on the limit equilibrium theory and cross‐sectional strain relationship. The predicted results of the proposed model agree well with test data. [ABSTRACT FROM AUTHOR]