Stiffness and Deformation Limit Performance of PC Beams Reinforced with Steel Sections

The prestressed steel-reinforced concrete beam (PSRCB) is a new type of composite beam developed by placing and tensioning prestressed tendons within ordinary steel-reinforced concrete beams (SRCBs). This type of beam combines the multiple advantages of steel, concrete, and prestressed reinforced concrete (PC) beams. It has high rigidity, high load-bearing capacity, small deformation, and good seismic performance. Compared to conventional SRCBs, PSRCBs have their own characteristics, and especially research on their stiffness and deformation has not been systematically reported. To investigate the stiffness and deformation resistance of PSRCBs, the design, fabrication, and loading tests of five PSRCBs were carried out, and relevant test data were obtained. By analyzing the test data, the calculation equation for the normal section stiffness of this type of composite beam was proposed. The stiffness of the PSRCB can be taken as the sum of the stiffness of the prestressed concrete beam and that of the built-in steel beam. Meanwhile, the calculation equations for the short-term stiffness of the PSRCB under the standard combination of load effects and the stiffness of the PSRCB considering the long-term influence of loads are obtained.