Research on strengthening of T-shaped reinforced concrete simply supported beams with U-shaped jackets to enlarge the cross-section: Theoretical analysis, experiments, and finite element analysis

To promote the reuse of existing beams, an experimental investigation was conducted on T-shaped reinforced concrete (RC) beams strengthened with U-shaped RC jackets. Three specimens were tested: one unstrengthened T-shaped control beam and two strengthened beams. Each jacket comprised additional reinforcing bars and higher-strength concrete cast along both sides of the web and the beam soffit, transforming the original T-shaped cross-section into a rectangular section. All three specimens were subjected to cyclic loading, and corresponding finite element simulations were performed to investigate their hysteretic response, skeleton response, flexural deformation, and failure modes. The strengthened beams exhibited load-carrying capacities more than twice that of the unstrengthened beam, and the finite element simulations generally reproduced the experimental responses. Based on truss–arch synergy, an analytical model was developed to predict the load-carrying capacity of RC beams. The predictions agreed well with the experimental results, supporting the reliability of the proposed model.