Flexural Performance Analysis of Composite Beam with Reinforced HPFRCC Precast Shell.

To enhance the mechanical properties of precast composite beams, High-Performance Fiber Reinforced Cementitious Composite (HPFRCC) material was used instead of ordinary concrete in the precast shell with reinforced bars to form the R/HPFRCC precast shell composite beam. By controlling different reinforcement ratios, post-longitudinal reinforcement treatment methods, mold shell materials, and loading methods, nine test beams were designed, and four-point bending loading tests were carried out to study the flexural bearing capacity, failure mode, failure process, deformation capacity, and influencing factors of composite beams. The R/HPFRCC prefabricated shell composite beams presented good mechanical performance and integrity. Compared with the RC shell composite beams, the R/HPFRCC prefabricated shell composite beam increased the yield and peak loads by 6.6% and 10.3%, respectively. Using HPFRCC material instead of ordinary concrete in the prefabricated shell could reduce the damage degree of the composite beam under bending. Under the same load, the reinforcement strain in the R/HPFRCC precast shell was smaller than that of the RC precast shell and the cast-in-situ RC beam; thus, the yield of longitudinal reinforcement was effectively delayed. Considering the HPFRCC material mechanical properties, a calculated model for the ultimate load-carrying capacity of R/HPFRCC precast shell composite beams was established. The calculated values were in good agreement with the experimental values.